When regular workouts and a healthy diet don’t quite help you fully realize your fat-loss goals, what recourse does a patient person have? Thermogenic dietary supplements — that is, substances that essentially increase your body temperature and the calories burned to help melt away superfluous fat.

“Thermogenesis (or heat production) has become synonymous with fat-burning,” explains Austin, Texas– based nutritional coach Tammy Thomas, MS, RD, CSCS. “Heat is produced as food is combusted in the body to create energy for work. Certain foods, herbs, drugs and natural processes can cause the body to produce more heat than energy, but even though this may seem inefficient, this wasted energy as heat may…result in greater fat oxidation and weight loss.”

Numerous fat-burning supplements will have a couple of components in common, such as caffeine or green tea, which are known for speeding up metabolism. But it’s the specialty ingredients that prompt the body to preferentially select fat as fuel for its energy fires instead of going to its standby, carbohydrate stores. Read on to learn about five hot ingredients in the fat-burning category.

Ingredient Name: Glutamine

What science says: The amino acid glutamine appears to promote fat oxidation, when the body burns fat for energy, according to Shawn Baier, assistant scientist in the department of food science and human nutrition at Iowa State University (Ames), who co-authored a study in the March–April 2006 Journal of Parenteral and Enteral Nutrition. “For the high-end fitness enthusiast or someone used to working out, glutamine could be something added to the fitness repertoire for that extra edge,” Baier says. “For the average American, sprinkling glutamine in their pop won’t help them lose 50 pounds, but glutamine supplementation appears to slightly increase fat oxidation. Over time, if you add up those small dosages and the little fat loss at each meal (meaning you actually burn some fat as energy for digestion because glutamine increases the body’s thermogenic response to food), that could give [fit females] an edge.”

What to consider: Glutamine isn’t very stable in liquid form and can degrade, so powders or capsules are the better way to go. Baier recommends mixing glutamine powder with plenty of cold water and drinking it within 24–72 hours for the best effects since the mixture will degrade if you leave it sitting.

Best way to use it: As the most abundant circulating amino acid in the human body, glutamine is naturally safe. The recommended dosage is 3–5 grams 3–4 times per day with one dose in the morning, one dose before workouts and one dose after workouts; if you take a fourth dose, take it later at night. Some individuals have trouble digesting large doses of glutamine, so start with a smaller dose and gradually increase the amount as your tolerance allows.

Ingredient Name: Coleus Forskohlii

What science says: Native to India, coleus forskohlii has been used for centuries in traditional medicine for everything from cardiovascular to gastrointestinal health. In May 2005 the Japanese publication Yakugaku Zasshi reported that coleus forskohlii reduced bodyweight, fat accumulation and appetite in female rats. A 2005 Journal of the International Society of Sports Nutrition study noted that coleus forskohlii has also been shown to prevent weight gain in women.

What to consider: Coleus forskohlii has been associated with increased heart rate and decreased blood pressure in some cases, according to the JISSN study’s authors, although the women in their trial did not experience those effects, which suggests it’s safe for most women to use.

Best way to use it: The recommended dosage is 20–50 mg 2–3 times daily.

Ingredient Name: Capsaicin

What science says: Capsaicin, the spicy component of chili peppers, is (not surprisingly) a source of heat inside the body. A June 2005 European Journal of Clinical Nutrition study showed capsaicin, when combined with green tea, calcium and tyrosine, promotes fat-burning without increasing the heart rate.

What to consider: As noted in the April 2006 International Journal of Obesity, capsaicin is an effective fat-burner on its own but even more so when combined with other fat-fighting ingredients such as tyrosine (500–100 mg), green tea extract (500 mg) and caffeine (200 mg).

Best way to use it: Look for capsaicin supplements that list Scoville thermal units or heat units and take enough to supply 40,000–80,000 units. If you can stand the heat, you could take a quarter-teaspoon of ground red pepper or cayenne pepper that lists the heat units. Take either one 30 minutes before meals to promote satiety, according to research in the June 2005 International Journal of Obesity, and stimulate thermogenesis and fat oxidation.

Ingredient Name: Sesamin

What science says: Found in sesame seeds, sesamin belongs to a class of phytoestrogens (compounds naturally occurring in plants) called lignans. In terms of its fat-burning capabilities, Japanese research published in the March 2006 issue of the journal Metabolism shows sesamin can increase fatty-acid oxidation by increasing enzyme activity in the liver.

What to consider: Combine sesamin with omega-3 fatty acids, such as those found in fish oil, to enhance its fat-oxidation effects, according to the study.

Best way to use it: Go with a dose of 500–1,000 mg 2–3 times per day with food.


The best way to find a safe product is to do the research. Read the label, the advertisements and any third-party literature displayed with the product. Check websites, such as the Food and Drug Administration (FDA), the Office of Dietary Supplements and the Natural Products Association (NPA) for recent news and research. Pay special attention to how claims are worded, as well. As noted in the Dietary Supplement Health and Education Act of 1994 (DSHEA) — the law governing supplements — dietary supplements can’t claim to “treat, cure, mitigate or prevent” disease.

Finally, always follow the instructions. “Consumers should pay close attention to the use instructions,” says Daniel Fabricant, PhD, vice president of scientific affairs at NPA. “With weight-loss products, many [people] tend to think more is better, and that isn’t always the case. Whether it’s food, supplements or any other consumer product, responsible use is the best policy.”

Photography by Mark Royce