When you’re shopping around for a thermogenic supplement, you want to choose one whose ingredients work best with your body. Learning what the key ingredients in these fat burners can do will help you create effective short- and long-term plans. Thermogenic supplements that are free of ephedra and other dangerous stimulants may help increase your metabolism and burn calories faster.

After the Food and Drug Administration (FDA) banned ephedra from the market, manufacturers of dietary supplements began researching alternative ingredients that could imitate the same reaction without harmful side effects. Now thermogenic formulas are made with a number of herbal extracts and synthetic ingredients.

Common Ingredients and Properties
Thermogenic supplements contain a variety of ingredients that can suppress the appetite, stimulate the nervous system, increase blood circulation, and even improve mood. While the FDA has not approved most of these supplements and ingredients, many do present themselves as “all natural” and “safe.” Understanding how each ingredient affects your body will help you make a better choice of supplement. We’ll cover some common ingredients in these supplements.

Garcinia cambogia
A small fruit, Garcinia cambogia contains the active ingredient hydroxycitric acid (HCA), considered a natural appetite suppressant. Because of this, Garcinia cambogia extract may help reduce preoccupations with food and eliminate the desire to eat large meals, although limited evidence is available on how effective the ingredient may be for weight loss in humans. Data from animal studies claim that HCA can reduce the formation of fats and cholesterol in the liver, along with reducing the appetite. It can be found in many thermogenic products such as Cytodyne Xenadrine, and combined with other herbs for enhanced effects.

L-carnitine
An amino acid, L-carnitine can be found both as a stand-alone supplement as well as an ingredient in fat burners such as Optimum Nutrition’s Mega Fat Burners. It supports natural fat loss and is commonly used in dietary supplements to provide a boost of energy. It may also increase the effects of vitamins E and C, aiding with preservation of lean body mass.

Synephrine
Also from Optimum Nutrition, Thermo-Cuts Extreme contains a powerful synephrine and caffeine formula that helps stimulate the central nervous system and may help with mental alertness, focus, and energy. While the effects may last for a few hours, the downside of synephrine is its addictive property; long-term use may lead to dependence, making it difficult to function without it. Despite this side effect, it’s used in many fat burners and appetite suppressants.

Bitter Orange
Synephrine is the active ingredient in bitter orange, also known as Citrus aurantium. A common ingredient in thermogenic supplements and appetite suppressants, bitter orange extract elevates the heart rate.

Green Tea Extract
Supplements such as Muscle Tech Hydroxycut contain a significant amount of green tea extract, a fat-burning ingredient. Green tea extract in a caffeinated form can provide a boost of energy and increase the heart rate, and green tea itself works as a natural antioxidant.

Not for Every Body
While it may take some trial and error for you to find the right formula for your body and nutritional needs, thermogenics that are free of ephedra are growing in popularity. However, if you have a history of heart disease, thyroid problems, high blood pressure, or diabetes, check with your doctor before beginning a fat-burning supplementation program.

—Sabah Karimi