Monday, February 16, 2009

Low Carb diet makes you happier?

Dr Briffa pointed this out (I'll have to interview him sometime!) People feel better on a low carb diet than they do on a low fat diet.

Here is the abstract:

Effects of two weight-loss diets on health-related quality of life
Purpose To compare the effects of two diets on health-related quality of life (HRQOL).
Methods Overweight volunteers (n = 119) were randomized to follow a low-carbohydrate, ketogenic diet (LCKD) or a low-fat diet (LFD) for 24 weeks. HRQOL was measured every 4 weeks using the Short Form-36 and analyzed using linear mixed-effects models.
Results The mean age was 45 years and mean baseline body mass index was 34 kg/m2; 76% were women. At 24 weeks, five subscales (Physical Functioning, Role-Physical, General Health, Vitality, Social Functioning) and the Physical Component Summary score improved similarly in both diet groups. Bodily Pain improved in the LFD group only, whereas the Role-Emotional and Mental Health subscales and the Mental Component Summary (MCS) score improved in the LCKD group only. In comparison with the LFD group, the LCKD group had a statistically significant greater improvement in MCS score (3.1; 95%CI 0.2–6.0; effect size = 0.44) and a borderline significant greater improvement in the Mental Health subscale (5.0; 95%CI −0.3–10.4; effect size = 0.37).
Conclusions Mental aspects of HRQOL improved more in participants following an LCKD than an LFD, possibly resulting from the LCKD’s composition, lack of explicit energy restriction, higher levels of satiety or metabolic effects.

It is not too surprising. Low fat diets have do not seem to be good for mental health. Barry Groves has an interesting story on his site.

Then there is this study - those whose serum cholesterol was below 4.27 mmol/l were six times more likely to attempt suicide than those with cholesterol above 5.77.

Low Serum Cholesterol Concentration and Risk of Suicide


Recent reports have suggested a link between low serum total cholesterol and risk of death from suicide. We examined this association using participants in the 1970-1972 Nutrition Canada Survey. We determined the mortality experience of Nutrition Canada Survey participants older than 11 years of age at baseline through 1993 by way of record linkage to the Canadian National Mortality Database. The relation between low serum total cholesterol and mortality from suicide was assessed using a stratified analysis (N = 11,554). There were 27 deaths due to suicide. Adjusting for age and sex, we found that those in the lowest quartile of serum total cholesterol concentration (<4.27 ratio =" 6.39;" interval =" 1.27-32.1)">5.77 mmol/liter). Increased rate ratios of 2.95 and 1.94 were observed for the second and third quartiles, respectively. The effect persisted after the exclusion from the analysis of the first 5 years of follow-up and after the removal of those who were unemployed or who had been treated for depression. These data indicate that low serum total cholesterol level is associated with an increased risk of suicide.


Anonymous said...

But here's a another one that contradicts it:

Jeff said...

Until someone suggests and provides some evidence for a CAUSAL mechanism I would not consider either study as particularly important.

Chris said...


There is a fair bit of science regarding the benefits of ketosis for brain function and mental function. Loads on the use of ketogenic diets for epilepsy treatment. But also see here for ideas regarding ketosis and dementia. Ketones appear to be neuroprotective.

Spector said...


All that study seems to say is that *at the highest threshold of serum cholesterol* people who commit suicide tend to use violent methods as opposed to nonviolent methods.

That is a wholly different statement then "high cholesterol increases suicide rate".