by Jose Antonio, Ph.D. Iron Man Magazine
Protein has the highest thermic effect of the three major macronutrients. In fact, one of the reasons that high-protein diets work so well vis-à-vis body composition is the elevated metabolic rate that comes with them. If you’re like me, however, you probably have wondered whether a liquid-protein shake is better (or not) than a solid meal when it comes to diet-induced thermogenesis, or DIT.
A recent study evaluated that exact issue. Resting metabolic rate and DIT response to a solid-meal (bar) vs. a liquid meal (shake) were measured in 19-to-28-year-old men who were sedentary, endurance trained or resistance trained.1 The researchers measured energy expenditure before and every 30 minutes after a meal for 210 minutes, or 3.5 hours.
Results: Resting metabolic rate was significantly higher in the endurance- and resistance-trained groups; however, when expressed per kilogram fat-free mass, the differences were not significant. So the muscles of folks who don’t work out are no different in terms of metabolic rate from those of folks who do work out. Both DIT (calories burned per minute) and relative DIT (calories burned per minute per unit of bodyweight) significantly increased with time from the resting metabolic rate for each meal form.
Interestingly, shakes produced a greater DIT (absolute and relative) than the solid meal in the resistance-trained group. In the sedentary group relative DIT from shakes was significantly lower than from bars. It seems a bit confusing, but if you regularly lift weights, liquid protein apparently is more thermogenic than solid protein. Yet the opposite occurs if you are a couch potato.
In other news, the diet/weight-loss market is always looking for new, cool ingredients to fight holiday flab. Here are few interesting tidbits. Carvacrol (2-methyl-5-isopropylphenol) is a “monoterpene phenolic constituent” of the essential oil produced by numerous aromatic plants and spices. Yeah, can you decipher that? Mice fed with this compound gained significantly less bodyweight and had lower visceral fat-pad weights and plasma lipid levels; carvacrol prevented obesity in mice by lowering bodyweight, visceral fat-pad weights and plasma lipid levels.2
Another study indicated that yerba mate has a potential anti-inflammatory effect. It also inhibits hepatic and muscle TNF-alpha and restores hepatic insulin signalling in mice with high- fat diet-induced obesity.3 In other words, this stuff is good for you.
And, of course, everyone’s favorite condiment, garlic, not only makes food taste amazing and wards off vampires but may also have an anti-obesity effect. A recent investigation concluded that “the antiobesity effects of garlic were at least partially mediated via activation of AMPK, increased thermogenesis and decreased expression of multiple genes involved in adipogenesis.”4
1 Ratcliff, L., et al. (2011). The influence of habitual exercise training and meal form on diet-induced thermogenesis in college-age men. Int J Sport Nutr Exerc Metab. 21(1):11-8.
2 Cho, S., et al. (2011). Carvacrol prevents diet-induced obesity by modulating gene expressions involved in adipogenesis and inflammation in mice fed with high-fat diet. J Nutr Biochem.
3 Arcari, D.P., et al. (2011). Anti-inflammatory effects of yerba mate extract (Ilex paraguariensis) ameliorate insulin resistance in mice with high fat diet-induced obesity. Mol Cell Endocrinol. 335(2):110-5.
4 Lee, M.S., et al. (2011). Reduction of body weight by dietary garlic is associated with an increase in uncoupling protein mRNA expression and activation of AMP-activated protein kinase in diet-induced obese mice. J Nutr. 141(11):1947-53.