The idiom “the fat is in the fire” usually denotes trouble ahead. However, exposing fat cells to extra heat is anything but a problem when weight loss is your goal.
Thermogenesis, the body’s natural heat production process, encourages fat cells to burn their stored calories and release them as additional heat. Consequently, adding “fire” to fat temporarily boosts metabolic rate and promotes fat loss.
Problems losing fat arise because factors like diet, age, and activity level often favor creating new fat cells over breaking down existing ones. That’s where fat burning supplements come in. These weight loss products increase thermogenesis beyond what the body does on its own, thereby supporting weight management.
But, examining the many supplements advertised as fat burners often raises more questions than it answers. Before you get discouraged, consult this list of supplement ingredients known to produce safe, predictable fat-burning effects.
Stimulants have both fans and critics in the supplement world. Detractors dislike stimulants’ potential side effects such as jitters and restlessness.
The reality is these side effects are largely preventable , and stimulants remain popular in many weight loss supplements because they are powerful and reliable. Following the directions and limiting additional stimulant consumption usually prevents side effects in most people.
No other stimulant is more commonly consumed worldwide than caffeine. Caffeine encourages fat cells to break down, leaving fewer and smaller fat cells behind. 
Caffeine also speeds metabolism, naturally converting those newly freed fatty acids into usable energy.  The energy boost caffeine provides enhances exercise performance and endurance. 
Caffeine increases thermogenesis in a dose-dependent manner; that is, the more caffeine consumed, the greater thermogenic increase. 
Caffeine-containing supplements need between 100 and 200 mg per serving to affect fat burning.
Usually taken from bitter orange extract, synephrine finds special receptors on fat cells to increase calorie burning.  Tests of a patented bitter orange extract show synephrine raises metabolic activity and makes fat burning supplements more efficient for weight management.
Although it’s often compared to ephedra, synephrine doesn’t cause the same negative side effects like speeding heart rate or raising blood pressure. 
Look for supplements that provide 30 to 60 mg synephrine per day. But, make sure there’s no more than 50 mg per single serving to ensure safety.
Although they’re chemically distinct from stimulants, these molecules also encourage fat-burning thermogenesis without affecting the central nervous system. These molecules all come from natural sources; the body even produces several on its own. Consequently, ingredients in this group provide great alternatives to stimulants while still producing measurable fat loss.
Although carnitine resembles essential amino acid, its main role isn’t to create protein molecules and muscle fibers. Rather, carnitine plays an essential role in transforming fat cells into ATP.
All cells use mitochondria to convert fat into energy. But, cells cannot go through their various energy production cycles without carnitine. With sufficient available carnitine, cells burn fat at an efficient rate. 
Typical dosages range from 1 to 3 grams daily. Many users take 500 to 1,000 mg carnitine with 2 or 3 meals.
Conjugated Linoleic Acid
It seems counterintuitive, but taking specialized fat molecules encourages fat cell breakdown. Of the “good” fats, conjugated linoleic acid molecules have some of the best evidence supporting them as fat-burning ingredients.
Research published in the American Journal of Clinical Nutrition details CLA’s fat loss effects in overweight adults. Participants in this study lost 7 to 9% body fat mass after 1 year of daily CLA supplementation. And, researchers noted CLA was the primary influence on this dramatic fat loss; diet and exercise were not major contributors to these results. 
Take up to 3.4 grams daily, usually with meals. Some sources recommend higher amounts, but medical experts question whether higher doses enhance CLA’s fat loss benefits.
7-Keto DHEA is not a hormone, but it is a byproduct of the parent hormone DHEA. Despite its hormonal origins, 7-keto DHEA affects fat-burning enzymes along with metabolic thyroid hormones.
7-keto DHEA activates enzymes and hormones that increase thermogenesis. That makes 7-keto DHEA a good fat-burning supplement for dieters. Normally, calorie restriction lowers total calories burned. But, people taking 200 mg 7-keto DHEA on a restricted calorie diet burned more calories. 
For weight loss, take a 100 mg dose twice daily. For best results, use 7-keto DHEA while following a regular exercise and diet program.
Not to be outdone by stimulants and other molecules, Mother Nature produces some plants with potent fat-burning components. Ranging from herbs to spices, these plant extracts reduce fat mass through thermogenesis just like the other ingredients in this article. In addition, these naturally sourced extracts often provide additional health benefits such as antioxidant protection from free radicals.
Green Tea Extract
Green tea extract contains powerful but natural chemicals known as catechins or polyphenols. The most potent of these chemicals is EGCG, which encourages thermogenesis.
A 2007 study linked catechin-rich green tea extract with reduced body fat, weight, BMI, and waist and hip circumference. Plus, participants also lowered blood pressure and cholesterol level after 12 weeks of green tea consumption. 
Daily intake of green tea extract should be between 1 and 3 g per day. Make sure the green tea extract has at least 50% EGCG.
Taken from a minty herb, forskolin extract revs metabolism and thermogenesis. Stored fat cells respond by releasing fatty acid molecules into the bloodstream. As forskolin burns away existing fat cells it also promotes lean mass gains. Men get an extra benefit from forskolin supplements: this herbal extract slightly raises testosterone levels. 
Health experts say 20% forskolin is the minimum potency capable of enhancing weight loss. A daily dose is usually 125 to 250 mg.
Capsaicin is the spice that causes your mouth to burn when you eat jalapenos and peppers. In fact, that sensation occurs along the entire digestive tract.
The result? Capsaicin heats up digestion, making the body burn more calories than it would digesting the same meal without the capsaicin. Capsaicin supplements take advantage of this spice’s heat, warming up metabolism no matter when you last ate.
Capsaicin’s efficacy is measured not in milligrams but in Scoville Heat Units, a scale of spice intensity. You need at least 40,000 SHU to get a major metabolic boost from a capsaicin supplement.
There are hundreds of different ingredients, but keep in mind these proven compounds when looking for the best fat-burning supplements!
 Keijzers, GB, BE De Galan, CJ Tack and P Smits. “Caffeine can decrease insulin sensitivity in humans.” Diabetes Care. 25.2 (2002): 364-9. Available from: http://www.ncbi.nlm.nih.gov/pubmed/11815511.
 Astrup, A, S toubro, et al. “Caffeine: a double-blind, placebo-controlled study of its thermogenic, metabolic, and cardiovascular effects in healthy volunteers.” The American Journal of Clinical Nutrition. 51.5 (1990): 759-767. Available from: http://ajcn.nutrition.org/content/51/5/759.short.
 Duncan, MJ, and SW Oxford. “The effect of caffeine ingestion on mood state and bench press performance to failure.” Journal of Strength and Conditioning Research. 25.1 (2011): 178-85. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21157384.
 Stohs, Sidney J., Harry G. Preuss, and Mohd Shara. “A Review of the Receptor-Binding Properties of p-Synephrine as Related to Its Pharmacological Effects.” Oxidative Medicine and Cellular Longevity. 2011. Available from: http://www.nutratechinc.com/advz/Studies2011/Mech%20of%20Action/M1%20Stohs%200611.pdf.
 Office of Dietary Supplements. “Dietary Supplement Fact Sheet: Carnitine.” National Institutes of Health. 2013 May 10. Available from: http://ods.od.nih.gov/factsheets/Carnitine-HealthProfessional/.
 Gaullier, Jean-Michel, Johan Halse, et al. “Conjugated linoleic acid supplementation for 1 y reduces body fat mass in healthy overweight humans.” American Journal of Clinical Nutrition. 79.6 (2001): 1118-25. Available from: http://ajcn.nutrition.org/content/79/6/1118.abstract.
 Zenk, JL, JL Frestedt, and MA Kuskowski. “HUM5007, a novel combination of thermogenic compounds, and 3-acetyl-7-oxo-dehydroepiandrosterone: each increases the resting metabolic rate of overweight adults.” The Journal of Nutritional Biochemistry. 18.9 (2007): 629-34. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17418559.
 Nagao, T, T Hase, and I Tomkimitsu. “A green tea extract high in catechins reduces body fat and cardiovascular risks in humans.” Obesity. 15.6 (2007): 1473-83. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17557985.
 Godard, M, B Johnson, and S Richmond. “Body composition and hormonal adaptations associated with forskolin consumption in overweight and obese men.” Obesity Research. 13.8 (2005): 1335-43. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16129715.