Wednesday, March 31, 2010

Intermittent Fasting Works

Here is an interesting study that indicates that Intermittent Fasting - as prescribed in Brad Pilon's Eat Stop Eat - works well for fat loss. ( Interviewed Brad Pilon here)

There are some good thoughts on the study here from the researchers:

The results defy the notion that fasting or dieting leads to gorging later; they also counter the idea that people have a genetically determined set point weight.

However, the study suggests a new strategy for losing weight. Although chronic lifestyle changes (eating healthier foods and getting more exercise) are preferable ways to lose weight, Levitsky said, a weekly fast might be another way to go.

Since it takes 10 to 14 days to recover the body tissue lost from a one-day fast, "Going without food for one day each week should produce a significant reduction in body weight over time," Levitsky said, now that we know that "fasting does not lead to overeating, and total recovery of body tissue does not occur within the week."

A useful study for those interesting in the science behind IF

One day of food restriction does not result in an increase in subsequent daily food intake in humans

The purpose of this study was to examine the effect of one day of food restriction on subsequent spontaneous daily food intake and the recovery of body weight in humans. Twenty-two, non-restrained females were fed from Monday to Friday for four weeks using food prepared and measured in the Cornell Metabolic Laboratory. For the first week, all participants ate ad libitum. For each subsequent Monday, participants were divided into three groups in which either they (a) ate ad libitum, (b) were restricted to eating 1200 kcal (5040 kj), or (c) were fasted. From Tuesday until Friday participants ate ad libitum. During each session, all food consumed as well as body weight were measured.

Body weight did not change following the day of ad libitum eating, but decreased significantly after the day of food restriction decreasing still further after fasting, indicating high compliance with study protocol. Although the loss in body weight was regained within four days, the recovery was accomplished without any increase in spontaneous food intake. Although no direct measurement of energy expenditure was made in this study, the results strongly suggest that decreases in metabolic rate play a more dominant role in the recovery of body weight following food restriction than the control of food intake.


Stephan said...

I don't find this study very informative. They didn't show that participants lost fat mass. All they showed is that they didn't compensate for calories lost after one single fast by eating more. There's no telling what the long-term reaction to IF would have been from what they showed.

Todd Hargrove said...

The researchers seemed impressed that participants didn't eat more to regain the weight, but instead just slowed their metabolisms to gain the weight back. Doesn't seem like such a great result to me and really what's the difference? This seems to confirm rather than refute the idea of a set point. The idea that you could somehow outrun the weight gain by fasting sooner than the weight gain occurs doesn't seem to make sense either. In the long term, wouldn't the body just learn to regain the weight to catch up with the fasting by either increasing hunger or slowing the metabolism even more?

williebr said...

I 2nd and 3rd.

Interesting anyway.

If it doesn't lead to an overall reduction in fat-mass who cares, even if the fat is not regained by overeating. It was regained.

However, I wonder what kind of diet these ladies were eating. Mixed? High carb, low fat?

In my personal and short experiment with v. low-carb IF (2 big meals/day... with 15hrs of a break) it is working like gang busters.

Who knows if that will last, or if that will work with many other people.

The Protein Review said...

It doesn't prove that their metabolism dropped, it just suggests that. You would have to specifically test the participants to confirm that their metabolic rate dropped. Other studies I've seen about metabolic rate show that it takes 3 days of continuous fasting before metabolic rate begins to change.

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