Dieting makes you fat.....

interesting stuff. 


Does dieting make you fat? A twin study

Exercise Bout Increases Metabolic Rate

The debate of whether or not exercise increases the metabolic rate post exercise floats around a fair bit.    Anyway this was just published:

A 45-Minute Vigorous Exercise Bout Increases Metabolic Rate for 14 Hours

INTRODUCTION: The magnitude and duration of the elevation in resting energy expenditure following vigorous exercise have not been measured in a metabolic chamber. This study investigated the effects of inserting a 45-min vigorous cycling bout into the daily schedule versus a controlled resting day on 24-h energy expenditure in a metabolic chamber.

METHODS: Ten male subjects (ages 22 to 33 yrs) completed two separate 24-h chamber visits (one rest and one exercise day) and energy balance was maintained for each visit condition. On the exercise day, subjects completed 45-min of cycling at 57% Wattsmax (mean±SD, 72.8±5.8% VO2max) starting at 11:00 am. Activities of daily living were tightly controlled to ensure uniformity on both rest and exercise days. The area under the energy expenditure curve for exercise and rest days was calculated using the trapezoid rule in the EXPAND procedure in the Statistical Analysis Systems (SAS) and then contrasted.

RESULTS: The 45-min exercise bout resulted in a net energy expenditure of 519±60.9 kcal (P<0.001). For 14-h post-exercise, energy expenditure was increased 190±71.4 kcal compared to the rest day (P±0.001).

CONCLUSION: In young male subjects, vigorous exercise for 45-min resulted in a significant elevation in post-exercise energy expenditure that persisted for 14-h. The 190 kcals expended post-exercise above resting levels, represented an additional 37% to the net energy expended during the 45-min cycling bout. The magnitude and duration of increased energy expenditure following a 45-min bout of vigorous exercise may have implications for weight loss and management.

 Pretty interesting.   It is soemthign that I have been thinking about recently - every workout has an impact:  hormonally on post exercise metabolic rate etc.  Every workout is important.

Can chilli peppers make you lose fat?

Possibly.....

Proteomic Analysis for Antiobesity Potential of Capsaicin on White Adipose Tissue in Rats Fed with a High Fat Diet

the scientists fed high-fat diets with or without capsaicin to lab rats used to study obesity. The capsaicin-treated rats lost 8 percent of their body weight and showed changes in levels of at least 20 key proteins found in fat. The altered proteins work to break down fats. (also here)

Training with Low Muscle Glycogen Enhances Fat Metabolism

This is a concept that hovers around a few training programmes and dietary approaches: training when you have low muscle glycogen either through prior intense exercise to deplete the glycogen (this is the approach Rusty takes in his Treadmill Ninja course) or via a low carb diet. Good to see a study to look at the concept.


Training in a state of glycogen depletion limited performance but increased fat burning. It would be interesting to see this compared with Phinney's work on low carb and endurance training.


Training with Low Muscle Glycogen Enhances Fat Metabolism in Well-Trained Cyclists.

PURPOSE:: To determine the effects of training with low muscle glycogen on exercise performance, substrate metabolism, and skeletal muscle adaptation. METHODS:: Fourteen well-trained cyclists were pair-matched and randomly assigned to HIGH or LOW-glycogen training groups. Subjects performed 9 aerobic training (AT; 90 min at 70% VO2max) and 9 high-intensity interval-training sessions (HIT; 8 x 5 min efforts, 1 min recovery) during a 3-wk period. HIGH trained once daily, alternating between AT on day 1 and HIT the following day, whereas LOW trained twice every second day, firstly performing AT and then 1 h later performing HIT. Pre and post-training measures were a resting muscle biopsy, metabolic measures during steady state cycling (SS), and a time trial (TT). RESULTS:: Power output during HIT was 297 +/- 8 W in LOW compared with 323 +/- 9 W in HIGH (P<0.05), however, TT performance improved by ~10% in both groups (P<0.05). Fat oxidation during SS increased after training in LOW (from 26+/-2 to 34+/-2 mumol/kg/min, P<0.01). Plasma FFA oxidation was similar before and after training in both groups but muscle-derived triacylglycerol oxidation increased after training in LOW (from 16+/-1 to 23+/-1 mumol/kg/min, P<0.05). Training with low muscle glycogen also increased beta-hydroxyacyl-CoA-dehydrogenase protein content (P<0.01).

CONCLUSION:: Training with low muscle glycogen reduced training intensity and, in terms of performance, was no more effective than training with high muscle glycogen. However, fat oxidation was increased after training with low muscle glycogen, which may have been due to enhanced metabolic adaptations in skeletal muscle.

To burn fat don't eat carbs before exercise - fast instead

Pasta.....maybe not! Actually it may be better to go into exercise fasted, if you are trying to burn fat (technical term = lipolysis).

Here is a study out today, which indicates that is you want to burn fat you should be going into exercise fasted or at least do not eat carbs within 2 hours. Sounds like another one for intermittent fasting enthusiasts.

We have said all this before of course. If you were taking a primal / evolutionary fitness perspective on all this you would be likely to be exercising when fasted anyway, if that exercise is the effort involved in a hunt for food. Lots of people out there are exercising fasted now as described here.

Effect of Carbohydrate- and Protein-rich Meals on Exercise-induced Activation of Lipolysis in Obese Subjects.

Exercise is an important part of obesity treatment concepts to support fat mobilisation from adipose tissue and also fat oxidation nolich is impaired in obese subjects. In normal weight subjects it is well known that stimulation of plasma insulin levels by a carbohydrate meal can inhibit lipolysis and subsequent fat oxidation. Since obese subjects frequently have elevated basal and postprandial insulin levels the effect of carbohydrate- and protein-rich test meals on exercise-induced activation of lipolysis is of special interest. Twenty obese subjects performed bicycle exercise for 30 min in the fasted state, 30 min after a carbohydrate-or a protein-rich meal, and 120 min after the carbohydrate meal (n=12), respectively, at low intensity. Activation of lipolysis was assessed by plasma glycerol levels. In addition, plasma insulin, glucose, and lactate concentrations were determined. In comparison to the fasted state, the carbohydrate meal suppressed activation of lipolysis. Following the protein meal, exercise led to an attenuated but significant increase of glycerol levels. A similar rise was observed when the carbohydrate meal was ingested 2 h prior to the exercise bout. To improve exercise-induced lipolysis and subsequent fat oxidation during low-intensity exercise obese subjects should not ingest carbohydrates immediately before exercise. Hunger sensations should be satisfied with protein-rich food. When carbohydrates are consumed 2 h prior to exercise its lipolytic effect is comparable to the protein meal. These data are useful in every day dietary counselling and might help to improve weight loss during obesity treatment.

When dieting doesn't work

Ok I know this is monkeys, but it is still interesting (but not really new)

Put monkeys on a diet and they do not lose weight because their activity levels fall to balance the reduction in food calories in. The body defends against weight loss from a diet by doing less.

Eat less and you will do less? The other side of this is the position Taubes takes - do more and you end up eating more anyway. (Especially with a calorie bomb recovery shake!)


Also note that it was a low fat diet - I wonder what the macros were for it? Often you find lab chow to be real junk - lots and lots of sugar and PUFA.

This is actually a rather depressing study the implication being that if you want to lose weight then you must:

• run on a treadmill for 1 hr/day, 5 days/week at 80% maximal capacity

Honestly it does't have to be that hard. (Remember Martin) There is a more natural way!


A Rapidly Occurring Compensatory Decrease in Physical Activity Counteracts Diet-Induced Weight Loss in Female Monkeys.

To study changes in energy balance occurring during the initial phases of dieting, eighteen adult female monkeys were placed on a low-fat diet with a 30% decrease in calories for one month. Surprisingly, there was not significant weight loss, however daily activity level (measured by accelerometry) decreased soon after diet initiation and reached statistical significance by the fourth week of dieting (18+/-5.6% decrease, p=0.02). During a second month of dieting, caloric intake was further reduced to 60% of baseline consumption, leading to 6.4+/-1.7% weight loss, and further suppression of activity. Metabolic rate decreased by 68+/-12 kcal/day; with decreased activity accounting for 41+/-9 kcal/day, and the metabolic activity of the weight lost accounting for 21+/-5 kcal/day. A second group of 3 monkeys was trained to run on a treadmill for 1 hr/day, 5 days/week at 80% maximal capacity, leading to increased calorie expenditure of 69.6+/-10.7 kcal/day (equivalent to 49 kcal/day for 7 days). We conclude that a diet-induced decrease in physical activity is the primary mechanism the body uses to defend against diet-induced weight loss, and undertaking a commonly prescribed exercise program for people seeking to improve fitness is sufficient to prevent the compensatory decrease in physical activity-associated energy expenditure that slows diet-induced weight loss.

Read more on these ideas at the Science of Sport blog here

intervals or low intensity to burn fat

This debate seems to keep going. One minute everyone is talking about EPOC and Afterburn and the advantages of interval training....then it is back to the advantages of long low intensity cardio to burn fat.....

Lyle McDonald had a good series on this recently....Anyway, here is another study...which seems to point towards the advantages of low intensity exercise. Then again...it is not as straightforward as that....

Fat oxidation rate during and after a low- or high-intensity exercise in severely obese Caucasian adolescents

Abstract The objective is to study the effects of low-intensity (LI) or high-intensity (HI) equicaloric exercises on energy expenditure (EE) and substrate oxidation rate during and after the exercises in severely obese Caucasian adolescents.

Twenty obese boys (BMI-SDS 3.04 ± 0.52, %Fat Mass 38.2 ± 2.1%) aged 14–16 years (pubertal stage >3) participated in this study. Maximal oxygen uptake (V′O2max) and maximal fat oxidation rate were determined with indirect calorimetry using a graded exercise test on a treadmill. EE and substrate oxidation rate during equicaloric low-intensity (LI, 42% V′O2max for 45 min) and high-intensity (HI, 67% V′O2max for 30 min) exercises on a treadmill and during post-exercise recovery period (60 min) were determined with indirect calorimetry. Maximal fat oxidation rate was observed at 42 ± 6% V′O2max (62 ± 5% HRmax) and fat oxidation rate was 0.45 ± 0.07 g/min.

The total amounts of EE, during the LI and HI exercises, and the post-exercise recovery periods were not significantly different (1,884 ± 250 vs. 1,973 ± 201 kJ, p = 0.453), but the total amount of fat oxidised was significantly higher (+9.9 g, +55.7%, p < 0.001) during the LI exercise than during the HI exercise. However, fat oxidation rates during the post-exercise recovery periods were not significantly different following LI and HI exercises.

Total fat oxidised was significantly higher during the LI than during the HI exercise in obese adolescents. However, the equicaloric exercise intensity did not influence EE, fat and carbohydrate oxidation rate during the recovery period.

A vacation body?

Rusty has put together a free little report on Building "a vacation body". It is free and has some good ideas on training and intermittent fasting.

You can get it here.

Stubborn Fat Loss....

This rings bells. The idea is that resistance exercise followed by an aerobic session makes you burn more fat than just doing the aerobic session.

It rings bells because it is seems to be basically Lyle MacDonald's prescription in the Stubborn Fat Solution, which I wrote about here.

Here is the study :

Effect of preceding resistance exercise on metabolism during subsequent aerobic session.

It appears that in training that combines both aerobic and resistance exercises, performing a comparatively higher intensity resistance exercise first would augment fat utilization and energy expenditure during subsequent aerobic exercise.

Anyone got any Leucine?

Leucine for retention of lean mass on a hypocaloric diet

ABSTRACT As obesity rates continue to climb, there is a pressing need for novel weight loss techniques. However, the energy-restricted diets recommended for weight loss typically result in significant amounts of lean tissue loss, in addition to the desired body fat loss. Leucine, a supported anticatabolic agent, has shown promise in research at many levels. First, leucine is known to stimulate the mammalian target of rapomycin pathway, which initiates translation and protein synthesis in muscle cells. Furthermore, leucine may help to regulate blood glucose levels by promoting gluconeogenesis. Finally, several recent studies provide evidence that leucine aids in the retention of lean mass in a hypocaloric state. The aim of this paper is to review relevant leucine research in the three areas described and assess its potential as supplement for obese individuals.

Ketogenic Mediterranean diet: a healthy cardiovascular diet for weight loss

Or so this new study says.....

It is interesting to look at the background:

Ketogenic diets are an effective healthy way of losing weight since they promote a non-atherogenic lipid profile, lower blood pressure and decrease resistance to insulin with an improvement in blood levels of glucose and insulin.

you don't hear that very often in the mainstream!

The whole article is currently available as a pdf

Here is the abstract:

Spanish Ketogenic Mediterranean diet: a healthy cardiovascular diet for weight loss

Background
Ketogenic diets are an effective healthy way of losing weight since they promote a non-atherogenic lipid profile, lower blood pressure and decrease resistance to insulin with an improvement in blood levels of glucose and insulin. On the other hand, Mediterranean diet is well known to be one of the healthiest diets, being the basic ingredients of such diet the olive oil, red wine and vegetables. In Spain the fish is an important component of such diet. The objective of this study was to determine the dietary effects of a protein ketogenic diet rich in olive oil, salad, fish and red wine.

Methods
A prospective study was carried out in 31 obese subjects (22 male and 19 female) with the inclusion criteria whose body mass index and age was 36.46 +/- 2.22 and 38.48+/-2.27, respectively. This Ketogenic diet was called "Spanish Ketogenic Mediterranean Diet" (SKMD) due to the incorporation of virgin olive oil as the principal source of fat ([greater than or equal to]30ml/day), moderate red wine intake (200-400ml/day), green vegetables and salads as the main source of carbohydrates and fish as the main source of proteins. It was an unlimited calorie diet. Statistical differences between the parameters studied before and after the administration of the "Spanish Ketogenic Mediterranean diet" (week 0 and 12) were analyzed by paired Student's t test.

Results
There was an extremely significant (p<0.0001)> 94.48 kg), body mass index (36.46 kg/m2->31.76 kg/m2), systolic blood pressure (125.71 mmHg->109.05 mmHg), diastolic blood pressure (84.52 mmHg-> 75.24 mmHg), total cholesterol (208.24 mg/dl->186.62 mg/dl), triacylglicerols (218.67 mg/dl->113.90 mg/dl) and glucose (109.81 mg/dl-> 93.33 mg/dl). There was a significant (p=0.0167) reduction in LDLc (114.52 mg/dl->105.95 mg/dl) and an extremely significant increase in HDLc (50.10 mg/dl->54.57 mg/dl). The most affected parameter was the triacylglicerols (47.91% of reduction).

Conclusions
The SKMD is safe, an effective way of losing weight, promoting non-atherogenic lipid profiles, lowering blood pressure and improving fasting blood glucose levels. Future research should include a larger sample size, a longer term use and a comparison with other ketogenic diets.

Insulin, Leptin and fish!

If you have been following Lyle's series on the Hormones of Bodyweight Regulation you will be familiar with the role of Leptin

Leptin signals to the brain that the body has had enough to eat, or satiety. A very small group of humans possess homozygous mutations for the leptin gene which leads to a constant desire for food, resulting in severe obesity. This condition can be successfully treated by the administration of recombinant human leptin.[1] Thus, circulating leptin levels give the brain input regarding energy storage so it can regulate appetite and metabolism. from wiki

Here is an interesting study which looks at Leptin and the way in which fatty fish, in the context of a calorie restricted diet, affects it:

Three servings a week of fatty fish included in an energy-restricted diet appears to be a valid strategy for specifically improving insulin sensitivity and leptin levels

Specific insulin sensitivity and leptin responses to a nutritional treatment of obesity via a combination of energy restriction and fatty fish intake.


Background Nutritional strategies to treat obesity often influence neuroendocrine factors related to body weight control. The present study aimed to investigate whether the inclusion of three fatty fish servings per week within a hypocaloric diet may have specific healthy effects on insulin and leptin functions. Methods Thirty-two subjects (body mass index = 31.6 +/- 3.5 kg m(-2)) aged 36 +/- 7 years, were assigned to a control or fish-based energy-restricted diet over an 8-week period. Anthropometry, body composition, lipid profile, leptin and insulin values were measured at the start and at the end of the dietary intervention. Results Both experimental diets resulted in a similar mean weight loss (control = 5.3 +/- 2.6% versus fish-based = 5.5 +/- 2.5%; P = 0.783). A significant reduction in insulin resistance, as determined by the homeostatic model assessment index (HOMA-IR = insulin x glucose/22.5), was observed after the fish-based intervention. The change in circulating leptin was higher in the fish-based diet compared to the control group. Sixteen percent of the variability in the change of adjusted-leptin could be explained (P = 0.034) by the HOMA index change and the type of diet. Conclusions Three servings a week of fatty fish included in an energy-restricted diet appears to be a valid strategy for specifically improving insulin sensitivity and leptin levels in obese subjects, which could involve a better body weight regulation after a nutritional intervention period.

Fat Loss Fast?

Warp Speed Fat Loss

Here is another product review. “Warp Speed Fat Loss” a new e book from Alwyn Cosgrove and Mike Rousell.

What is it?

Well you can get an idea from the title. It is a combination of diet and training that purports to deliver fast fat loss - weight loss of 8lbs in the first week and up to 21lbs in 28 days is possible…...

It is a very prescriptive programme in that you are told day by day and meal by meal what you should eat and how you should train.

There are two main aspects to the programme - diet and training. The diet lays out a 28 day diet plan based on your current weight and the training similarly lays out
a series of workouts – interval sessions, metabolic style weight training and cardio.

Who is it for?

Now you could create your own programme with all of these elements. There are enough resources out there on the interwebs to tell you what to do – e.g. one part of this plan is very similar to this.

However, most people do not have the time or the inclination or – to be honest - the intelligence to put together their own programme. Most people want to be told what to do. They do not want to think for themselves. If that is you - and it is nothing to be ashamed of - then check out Warp Speed Fat Loss.

If you enjoy the science and the programme design, know about cycling your carbs etc then you don’t need this product. If you are looking for a step by step prescription telling you what to do, then you might want to try it.

The advanced, the independent would probably be happier reading Lyle’s stuff. But I know that many people want to be trained rather than to train themselves. This takes away the thinking and gives you some basics that should work– if you do what you are told.

What do you get?

A 478 page colour pdf with menu plans and workouts specified for the 4 weeks of the plan, plus some explanations of why these prescriptions are made.

What don’t I like?

• The marketing…..It may just be me, but the sort of advertising copy that is so prevalent on the internet puts me off. I am sure that it is successful – this sort of copy has been developed "scientifically" over years in the direct marketing field. However it all gets a bit formulaic: testimonials, bullet points, special free gifts, ps, pps etc
• The fact that it is an ebook. I know that you can print these things out, but I like to hold a book in my hands and write on it myself or whatever. At 478 pages I think I’d be sacked from work if I tried to print this one out when the bosses back was turned!

Summary

In a previous post I talked about those who are Artists, Scientists or Accountants.

Warp Speed Fat Loss probably wouldn’t suit the artist – there is too much science, too much prescription. The scientist would have their appetite whetted, but if they wanted to look more deeply into the physiology of what is going on then they would have to look elsewhere. Perhaps this is for the accountant who is prepared to do exactly what is prescribed, step by step.

Low carb wins?

All you low carb dieters out there will probably be aware of a new study:

Systematic review of randomized controlled trials of low-carbohydrate vs. low-fat/low-calorie diets in the management of obesity and its comorbidities

Evidence from this systematic review demonstrates that low-carbohydrate/high-protein diets are more effective at 6 months and are as effective, if not more, as low-fat diets in reducing weight and cardiovascular disease risk up to 1 year.

Both Eades and Briffa has commentaries on the study.

By the way, I am becoming less dogmatic about low carb than I used to be. I have started to introduce some more carbs - mainly potatoes and oatmeal - to my diet especially around my workouts and Stephan's recent posts on the Kitava study are explaining that high carb inteake per se is not necessarily a bad thing:

In my opinion, the most important finding in this paper is that a high-carbohydrate diet does not necessarily lead to elevated fasting insulin. This is why I think the statement "carbohydrate drives insulin drives fat" is an oversimplification. What drives fat accumulation is chronically high insulin (hyperinsulinemia), which the Kitavans do not have. With a properly-functioning pancreas and insulin-sensitive tissues (which many people in industrial societies do not have), a healthy person can eat a high-carbohydrate meal and keep blood glucose under control. Insulin definitely spikes, but it's temporary. The rest of the day, insulin is at basal levels. The Kitavans show that insulin spikes per se do not cause hyperinsulinemia.

Watch your weekend

I generally tend to loosen up a bit on the weekend regarding diet. I don't go mad...but I'll maybe have some bread with breakfast, or a chinese take away. Maybe some beers. And to be honest I think that is Ok, given that the obsessive focus that I sometimes give to diet and exercise is not really healthy. it is good to loosen up a bit.

However, this is a new study that would indicate that you need to be aware of the danger of getting too loose on the weekend.....folks tend to eat more the weekend....and do less exercise and that can accumulate.

This is from the latest issue of Obesity

Influence of Weekend Lifestyle Patterns on Body Weight

Objective: To determine whether alterations in diet and/or activity patterns during weekends contribute to weight gain or hinder weight loss.

Methods and Procedures: Randomized, controlled trial comparing 1 year of caloric restriction (CR) with 1 year of daily exercise (EX). Subjects included 48 healthy adults (30F, 18M) aged 50–60 years with BMI 23.5–29.9 kg/m2. Body weight was measured on 7 consecutive mornings for a total of 165 weeks at baseline and 437 weeks during the 1-year interventions. Daily weight changes were calculated for weekends (Friday to Monday) and weekdays (Monday to Friday). Daily energy intake was estimated using food diaries; daily physical activity was measured using accelerometers. Both measures were validated against doubly labeled water (DLW).

Results: At baseline, participants consistently gained weight on weekend days (+0.06 0.03 kg/day, (mean s.e.), P = 0.02), but not on weekdays (-0.02 0.02 kg/day, P = 0.18). This was attributable to higher dietary intake on Saturdays and lower physical activity on Sundays relative to weekdays (both P < 0.05). During the interventions, both CR and EX participants were in negative energy balance on weekdays (P < 0.005). On weekends, however, CR participants stopped losing weight, and EX participants gained weight (+0.08 0.03 kg/day, P < 0.0001) due to higher dietary intakes on weekends. This helps to explain the slower-than-expected rate of weight loss during the interventions.

Discussion: Alterations in lifestyle behaviors on weekends contribute to weight gain or cessation of weight loss on weekends. These results provide one explanation for the relatively slow rates of weight loss observed in many studies, and the difficulty with maintaining significant weight loss.

Long-Term Weight Loss Requires Almost Double Suggested Amount of Exercise

This one is quite thought provoking....

Standard recommendations for 30 minutes of exercise five days a week won't cut it to sustain weight loss, researchers said.

There is a good commentary here, but the idea is that people often think that they can get by with diet alone. You need exercise - it is a package deal!

Effect of Exercise on 24-Month Weight Loss Maintenance in Overweight Women

Background Debate remains regarding the amount of physical activity that will facilitate weight loss maintenance.

Methods Between December 1, 1999, and January 31, 2003, 201 overweight and obese women (body mass index [calculated as weight in kilograms divided by height in meters squared], 27 to 40; age range, 21-45 years) with no contraindications to weight loss or physical activity were recruited from a hospital-based weight loss research center. Participants were assigned to 1 of 4 behavioural weight loss intervention groups. They were randomly assigned to groups based on physical activity energy expenditure (1000 vs 2000 kcal/wk) and intensity (moderate vs vigorous). Participants also were told to reduce intake to 1200 to 1500 kcal/d. A combination of in-person conversations and telephone calls were conducted during the 24-month study period.

Results Weight loss did not differ among the randomized groups at 6 months' (8%-10% of initial body weight) or 24 months' (5% of initial body weight) follow-up. Post-hoc analysis showed that individuals sustaining a loss of 10% or more of initial body weight at 24 months reported performing more physical activity (1835 kcal/wk or 275 min/wk) compared with those sustaining a weight loss of less than 10% of initial body weight (P < .001).

Conclusions The addition of 275 mins/wk of physical activity, in combination with a reduction in energy intake, is important in allowing overweight women to sustain a weight loss of more than 10%. Interventions to facilitate this level of physical activity are needed.

High Carb diet makes it harder to burn fat?

What do you make of this? (my understanding of this science is still developing, but Lyle McDonald's Stubborn Fat Loss Solution is helping a lot)

The study indicates that a short term high carb diet leads to a decrease in the amount of fat that is burned and an increase in the amount of fat that is stored in muscle and liver. That is not good.

UPDATE - thinking about it, I suppose this does make sense since (from Lyle) insulin impairs fat mobilisation and carbs drive insulin. So if the fat is not getting out of the fat cells you can't burn it.

Reduced oxidation of dietary fat after a short term high-carbohydrate diet.


BACKGROUND: Short-term high-carbohydrate (HC) diets induce metabolic alterations, including hypertriacylglycerolemia, in both the fasting and postprandial states. The underlying tissue-specific alterations in fatty acid metabolism are not well understood.
OBJECTIVE: We investigated alterations in exogenous and endogenous fatty acid metabolism by using stable isotope tracers to label meal triacylglycerol and plasma fatty acids.
DESIGN: Eight healthy subjects consumed isocaloric diets containing a high percentage of energy from carbohydrates or a higher percentage of energy from fat for 3 d in a randomized crossover dietary intervention study. A test meal containing [U-13C] palmitate was combined with intravenous infusion of [2H2] palmitate to label plasma fatty acids and VLDL triacylglycerol. Blood and breath samples were taken before the meal and for 6 h postprandially. Blood samples were drawn from the femoral artery and from veins draining subcutaneous adipose tissue and forearm muscle for monitoring of tissue-specific metabolic substrate partitioning.
RESULTS: Systemic triacylglycerol concentrations were increased in both fasting (P = 0.02) and postprandial (P = 0.02) periods, and a greater amount of infused labeled fatty acid appeared in VLDL triacylglycerol after the HC diet than after the higher-fat diet (P = 0.05). Significantly less 13CO2 was exhaled after the HC diet (P = 0.04) and significantly less production of 13CO2 was seen across forearm muscle (P = 0.04). Systemic 3-hydroxybutyrate was significantly lower, postprandially, after the HC diet (P = 0.02).
CONCLUSION: Metabolic alterations suggestive of repartitioning of fatty acids away from oxidation toward esterification in both liver and muscle occur in response to short-term adaptation to a HC diet.

Intermittent Fasting - another mechanism

There are quite a few of us now that have an interest in Intermittent Fasting (IF). I have just seen this abstract which looks at another mechanism associated with IF. This mechanism could add to the fat-burning effect of fasting.

You may have heard of l-carnitine - it has been sold as a supplement allegedly to increase fat burning and prevent fatigue. The description below is from Wikipedia:

Carnitine, also known as L-carnitine or levocarnitine, is a quaternary ammonium compound biosynthesized from the amino acids lysine and methionine.[1] It helps in the consumption and disposal of fat in the body because it is responsible for the transport of fatty acids from the cytosol into the mitochondria. It is often sold as a nutritional supplement.

One of the supplement advertisements explains:

L-carnitine transfers long-chain fatty acids, such as triglycerides into mitochondria (a cell's energy powerhouse), where they may be oxidized to produce energy. L-carnitine is a very popular supplement that promotes growth and development. It is also used for fat-burning, increasing energy, and improving resistance to muscle fatigue. L-carnitine has also been shown to help build muscle. is also great in dieting, as it reduces feelings of hunger and weakness.

OK, that is the context.

Now there is this study, Fasting and Caloric Restriction Increases mRNA Concentrations of Novel Organic Cation Transporter-2 and Carnitine Concentrations in Rat Tissues.

The study shows that fasting and caloric restriction lead to an upregulation of OCTN2 in several tissues, probably mediated by activation of PPAR. Increased tissue carnitine concentrations in fasted and calorie-restricted rats might be at least in part due to increased uptake of carnitine by OCTN2.


The study identifies a particular mechanism but the key issue is that fasting and calorie restriction (CR) lead to increased carnitine concentrations.


So that which athletes and bodybuilders seek to achieve via supplementation is possible - at least in rats - via fasting or calorie restriction...



Background: Recently, we have shown that activation of peroxisome proliferator-activated receptor (PPAR)- by clofibrate leads to an upregulation of novel organic cation transporter (OCTN)-2, a carnitine transporter, and in turn increases the carnitine concentration in the liver of rats. In this study, we tested the hypothesis that fasting and caloric restriction, conditions under which PPAR activation also occurs, cause similar effects. Methods: Three groups of rats received the diet either ad libitum (control rats) or 10.5 g diet/day (70% of energy requirement for maintenance, E70 rats) or 6 g diet/day (40% of energy requirement for maintenance, E40 rats) for 10 days. A 4th group received the diet ad libitum for 9 days and was then fasted for 24 h (fasted rats). Results: Fasted and calorie-restricted rats had increased mRNA concentrations of acyl-CoA oxidase and carnitine palmitoyltransferase-1 in the liver, heart and kidneys compared to control rats (p < 0.05), indicative of activation of PPAR in these tissues. E70 rats had increased OCTN2 mRNA concentrations in liver (2.6-fold) and kidneys (1.5-fold) and increased total carnitine concentrations in these tissues compared to control rats. E40 rats had increased OCTN2 mRNA concentrations in the liver (3.3-fold), skeletal muscle (2.2-fold), heart (2.3-fold) and kidneys (3.5-fold) and increased total carnitine concentrations in these four tissues compared to control rats. Fasted rats had increased OCTN2 mRNA concentrations in the liver (4.0-fold), heart (2.1-fold) and kidneys (2.0-fold) and increased total carnitine concentrations in these three tissues (p < 0.05). Conclusion: The study shows that fasting and caloric restriction lead to an upregulation of OCTN2 in several tissues, probably mediated by activation of PPAR. Increased tissue carnitine concentrations in fasted and calorie-restricted rats might be at least in part due to increased uptake of carnitine by OCTN2.

Eating Carbs after your workout reduces the fat burning effect?

If you want to maximise the fat burning effect of effect of exercise, what should you eat after a workout? This study - and the full paper is currently available here - seems to indicate that you should keep away from a carbohydrate rich meal. It is a really interesting paper to read and what I get from it is that having a carb rich meal after a workout blunts the fat burning effect generated by the exercise. Have a read - see what you think.

Devany gives another reason not to eat carbs after the workout

Does prior acute exercise affect postexercise substrate oxidation in response to a high carbohydrate meal?

BACKGROUND: Consumption of a mixed meal increases postprandial carbohydrate utilization and decreases fat oxidation. On the other hand, acute endurance exercise increases fat oxidation and decreases carbohydrate utilization during the post-exercise recovery period. It is possible that the resulting post-exercise increase in circulating nonesterified fatty acids could attenuate the ability of ingested carbohydrate to inhibit lipid oxidation. The purpose of this study was to determine whether prior exercise attenuates the usual meal-induced decline in lipid oxidation.
METHODS: Six healthy, physically active young subjects (x age = 26.3 years, 4 males, 2 females) completed three treatments in random order after a ~10 h fast: (a) Exercise/ Carbohydrate (Ex/CHO): subjects completed a bout of exercise at 70% VO2peak (targeted net energy cost of 400 kcals), followed by consumption of a carbohydrate-rich meal; (b) Exercise/Placebo (Ex/Placebo): subjects completed an identical bout of exercise followed by consumption of a placebo; and (c) No Exercise/Carbohydrate (NoEx/CHO): subjects sat quietly rather than exercising and then consumed the carbohydrate-rich meal. Blood samples were obtained before and during the postprandial period to determine plasma glucose, insulin, and non-esterified fatty acids (NEFA). Respiratory gas exchange measures were used to estimate rates of fat and carbohydrate oxidation.
RESULTS: Plasma NEFA were approximately two-fold higher immediately following the two exercise conditions compared to the no-exercise condition, while meal consumption significantly increased insulin and glucose in both Ex/CHO and NoEx/CHO. NEFA concentrations fell rapidly during the 2-h postprandial period, but remained higher compared to the NoEx/CHO treatment. Carbohydrate oxidation increased rapidly and fat oxidation decreased in response to the meal, with no differences in the rates of carbohydrate and fat oxidation during recovery between the Ex/CHO and NoEx/CHO conditions.
CONCLUSION: The plasma NEFA concentration is increased during the post exercise period, which is associated with elevated fat oxidation when no meal is consumed. However, when a mixed meal is consumed immediately following exercise, the initially elevated plasma NEFA concentration decreases rapidly, and postexercise fat oxidation during this 2-h postexercise, postprandial period is no higher than that of the 2-h postprandial period without prior exercise.

Lose fat off your legs and trunk with interval training

8 seconds on 12 seconds off

I've talked about this researcher before, Gail Trapp has been looking at interval training and fat loss for her PhD, titled:

Effect of High Intensity Exercise on Fat Loss in young Overweight Women

Like any good research scientist, she is getting as many papers out of this research as she can! He is another one in the International Journal of Obesity:

The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women

Objective: To determine the effects of a 15-week high-intensity intermittent exercise (HIIE) program on subcutaneous and trunk fat and insulin resistance of young women.
Design and procedures: Subjects were randomly assigned to one of the three groups: HIIE (n=15), steady-state exercise (SSE; n=15) or control (CONT; n=15). HIIE and SSE groups underwent a 15-week exercise intervention.
Subjects: Forty-five women with a mean BMI of 23.22.0 kg m-2 and age of 20.22.0 years.
Results: Both exercise groups demonstrated a significant improvement (P<0.05) in cardiovascular fitness. However, only the HIIE group had a significant reduction in total body mass (TBM), fat mass (FM), trunk fat and fasting plasma insulin levels. There was significant fat loss (P<0.05) in legs compared to arms in the HIIE group only. Lean compared to overweight women lost less fat after HIIE. Decreases in leptin concentrations were negatively correlated with increases in VO2peak (r=-0.57, P<0.05) and positively correlated with decreases in TBM (r=0.47; P<0.0001). There was no significant change in adiponectin levels after training.
Conclusions: HIIE three times per week for 15 weeks compared to the same frequency of SSE exercise was associated with significant reductions in total body fat, subcutaneous leg and trunk fat, and insulin resistance in young women.

Intervals are better...

So, high intensity intervals are better than steady state exercise (long boring cardio...) in terms of:

• reducing total body fat;
• reducing leg and trunk fat; and
• reducing insulin resistance.
  

Despite the hyped up sales page (why do people do that?) PACE is a good introduction to the science behind interval training.

Joel also has some regular sprint workouts.


Other related posts:

• Sprints increase fat mobilisation
  
• Interval Training - 8 Seconds for fat loss
• 8 seconds for Fat Loss