By Richard B. Kreider, PhD, FACSM, FISSN
It seems you can’t open a magazine, turn on the television, or listen to the radio without hearing an advertisement about a fat-loss supplement. While it used to be easy to dismiss these types of advertisements as gimmicks, the truth is that we have come a long way in understanding that certain nutrients can affect fat metabolism, fat digestion, appetite and/or weight. Research has shown that some of these supplements can play an important role in helping people lose and/or maintain weight after fat loss. These supplements generally fall within one of five categories: meal replacements, thermogenics, fat metabolizers, fat blockers and appetite suppressants.1
So which are worth your hard-earned money? Read on.
Most of the products in this category represent low-fat/high-protein food alternatives.3 They typically consist of pre-packaged food bars, meal-replacement powders (MRP) or ready-to-drink (RTD) supplements. They are designed to serve as a lower calorie meal replacement or a low-fat snack to help people follow a diet.
Research has generally shown that if you replace a meal with a MRP or RTD, you typically lose weight by reducing total caloric intake. For example, Cheskin and co-workers4 reported that a diet using portion-controlled meal replacements yielded significantly greater initial weight loss and less weight regain after one-year follow-up than a standard self-selected food-based diet in patients with type 2 diabetes. The composition of the meal replacement may also influence results. For example, Treyzon and associates5 evaluated the effects of ingesting a high-protein (2.2 grams of protein per kg of lean mass) or high-carbohydrate (1.1 grams of protein per kg of lean mass) isocaloric meal replacement for 12 weeks on weight loss in 100 obese men and women.
Subjects ingesting the high-protein meal replacement lost significantly more fat mass (-3.6 lbs) than those consuming the high-carbohydrate meal replacement (-01.4 lbs). The type of meal replacement may also influence appetite. Thicker liquid meal replacement drinks suppress appetite to a greater degree than less dense drinks.6 In addition, meal replacement bars have been reported to be more satisfying in terms of reducing hunger than liquid meal replacements.6 These findings and others suggest that if you want to lose weight, meal-replacement bars and drinks certainly can help!
Thermogenics are supplements designed to increase resting energy expenditure and promote weight loss. For many years, most thermogenic supplements contained the “ECA” stack of ephedra alkaloids (e.g., ma huang, 1R,2S Nor-ephedrine HCl, Sida cordifolia), caffeine (e.g., guarana, bissy nut, kola) and aspirin/salicin (e.g., willow bark extract). Although a significant amount of research showed efficacy and safety of use of these supplements in healthy populations to promote weight loss,7,8 the Food and Drug Administration (FDA) banned the sale of dietary supplements containing ephedra alkaloids, citing safety concerns. Since then, most thermogenic supplements contain a combination of green tea extract, guarana (naturally-occurring caffeine), synephrine (e.g., Citrus aurantium, bitter orange), willow bark (a naturally occurring form of aspirin), capsicum (chili pepper), etc.10,11
A number of studies have found that ingestion of these types of supplements can increase energy expenditure.11-14 For example, Taylor and colleagues12 reported that ingestion of a coffee-containing green tea with extra caffeine increased resting energy expenditure (REE) by 14 percent, compared to a slight decrease in the coffee-only group. Rudelle and workers14 reported that ingestion of three 250ml servings of a beverage containing green tea, caffeine and calcium for three days, significantly increased 24-hour energy expenditure. In another study, Boschmann, et al.13 reported that ingestion of 300mg/day of green tea for two days significantly increased fat oxidation compared to controls. In another study, Auvichayapat and associates16 investigated the effects of supplementing the diet with green tea in obese individuals administered a diet. Participants who ingested green tea during the diet lost significantly more weight (5.9 to 11.2 pounds) and had a higher REE than subjects dieting while taking a placebo.
These findings support contentions that ingestion of green tea and caffeine can increase resting energy expenditure. There is also some preliminary evidence that chronic intake of green tea and caffeine can promote weight loss and/or help maintain weight after weight loss. For example, Westerterp and colleagues15 reported that habitual caffeine consumers were able to maintain weight loss after dieting to a greater degree than low-caffeine consumers. Moreover, supplementation of a green tea/caffeine mixture helped maintain weight loss in the group of habitually low-caffeine consumers. Collectively, these findings suggest that ingesting green tea and caffeine can increase resting metabolism, leading to greater weight loss over time.