Dietary protein affects lean weight gain, but not fat gain, during overeating

A January 2012 JAMA study reports that people eating 40% more calories than they expended for eight weeks gained the same amount of body fat regardless whether they ate protein at 5% (low protein), 15% (normal protein), or 25% (high protein) of calories.

But the amount of lean (muscle) weight gain (and thus total weight gain) and resting energy expenditure were influenced by the amount of protein eaten.

The weight gain in the low protein diet group was 3.16 kg, about half that of the other 2 groups (normal protein diet: 6.05 kg; high protein diet: 6.51 kg; P = .002). The rate of weight gain in the low protein diet group was significantly less than in the other 2 groups (P < .001). The failure to increase lean body mass in the low protein group accounted for their smaller weight gain [emphasis added]. …

Resting energy expenditure, total energy expenditure, and body protein did not increase during overfeeding with the low protein diet. In contrast, resting energy expenditure … and body protein (lean body mass) … increased significantly with the normal and high protein diets. Continue reading

Saturated fat is OK if carbs aren’t too high

Eating saturated fat keeps appearing less harmful and more beneficial than previously thought.

A 2010 meta-analysis of prospective human studies found “that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD [coronary heart disease] or CVD [cardiovascular disease including stroke].”

And late last year, a University of Alabama study lent support to some paleo-like diets, higher in saturated fats and low to moderate in carbohydrates. Continue reading

Keep eating, say fat people’s brains

More on brain changes in obesity:

An April 2011 Nature article by French researchers demonstrated that diet-induced obesity in miniature pigs leads to decreased activation of the prefrontal cortex, a brain region used for “inhibition of inappropriate behavior, satiety, and meal termination.”  The brain activation was determined by regional blood flow as measured by SPECT imaging.

Like the pigs, obese men also show reduced activation of their prefrontal cortex, and it’s not known whether these brain changes cause obesity, or obesity causes the brain changes. Continue reading