What Do Fat Burners Do?

Think of fat burners like a scope on a hunting rifle, only you're trying to hunt fat cells.

In this metaphor, your diet is the gun, and exercise is the ammunition. Fat burners may help you aim a bit better and target fat more efficiently. But without the heavy artillery of your diet, and some bullets in the chamber, a scope is just good for looking at things from far away—not for bringing home results!

So, what is a fat burner? As explained in the journal Obesity Reviews, the term "fat burner" is used to describe "nutrition supplements that are claimed to acutely increase fat metabolism or energy expenditure, impair fat absorption, increase weight loss, increase fat oxidation during exercise, or somehow cause long-term adaptations that promote fat metabolism."[1] However, that's a wide range of functions, and in pill form especially, it can mean a lot of things! So, let's dig a little deeper.

How do fat burners work? Some of the key ingredients used in fat burners are designed to stimulate hormonal reactions in the body, and to begin breaking down fat and using it as a fuel source.

The main ingredient in most fat burners is caffeine, which helps you lose weight by increasing your metabolism and helping the body use fat for fuel. It also helps provide energy for exercise and other calorie-burning activities. In the body, caffeine increases the breakdown of fatty acids that reside in adipose tissue—also known as belly fat. Once the fatty acids are broken down, they enter the bloodstream and can be burned up by our bodies to create energy.

One thing a fat burner won't do, however, is fix a broken diet. If you're eating for healthy fat loss, the way Krissy Kendall, Ph.D., explains in the comprehensive guide "How to Lose Weight," then a thermogenic fat burner can help with the other stuff: boosting energy, helping to curb appetite, promoting fat to be used for energy, and even increasing your metabolism and core temperature—what is known as "thermogenesis"—so you burn more calories throughout the day.

Do Fat Burners Work?

Yes, they do…as long as you have reasonable expectations of what a fat burner "working" means.

Some people believe if they're using a fat burner, they should be able to melt huge amounts of fat off each week. Not gonna happen! But here are some ways you can help a fat burner do its work.

Set reasonable expectations: While your rate of fat loss can be enhanced with supplements, you won't be dropping 10 pounds in a week simply because you're using a thermogenic supplement. Sorry!

Remember this number: A safe rate of fat loss is 1-3 pounds per week, for average, healthy individuals. You can push this rate up to 4 pounds per week on rare occasions, but it's not sustainable. Eventually, your body will hit a plateau and fat loss will slow.

If you're dropping weight too quickly, on a fat burner or not, you could be losing lots of lean muscle mass. Unless you want to look like a shapeless coat hanger—and feel as healthy and athletic as one—you should rethink your fat-loss plan.

Set your weight-loss goals from week to week and month to month, not day to day. When you meet incremental goals over time, you'll stay more motivated and see great results from your program. Sure, some weeks you may not see any results—that's to be expected. But with the help of a fat burner, your fat loss will stay on track over the longer term.

Cycle your fat burner: Even the best thermogenic fat burner won't keep giving results forever. Sorry!

"Many people use thermogenics because they can help reach weight-loss goals in a shorter period of time. They can also boost energy levels at the gym. But chronic usage can increase your tolerance," explains Krissy Kendall, Ph.D., in the article "What Supplements Should I Be Cycling?"

"I encourage people to cycle their fat burners," Kendall explains. "People are typically on a fat burner for 4-6 weeks. Once your body gets used to it, you're not going to see the same increase in fat oxidation or increase in metabolic rates. By stopping using your fat burner every now and then, you make sure it will still help you lose belly fat."

The only problems she says, is that since caffeine is considered a drug, you can experience withdrawal effects when you stop taking it.

"The withdrawal effects are the worst 1-2 days without it, and they linger on for about seven days," Kendall says, "but most people will say after about a week of it, your body starts to adapt to life without it."

Kendall recommends staying off your fat burner for a couple weeks, then starting back up again—ideally at a lower dose that what you were taking before you stopped.

Start at a low dose: Fat burners are designed specifically to give you the proper doses of various ingredients to support fat loss. But that doesn't mean that the more of the ingredients you take, the more results you'll see. Supplement manufacturers state the serving guidelines and directions so you can have a way of measuring what dose works best for you.

It's always best to start with the lowest dose listed on the package and stay at that dose for at least two weeks. After that, you can determine if you want to bump up the dose to the higher end of the spectrum if it's listed on the packaging. If the product lists only one serving size, don't go above it.

Make muscle a priority: It's a common approach to simply take a thermogenic, hop on the nearest cardio machine, and dream of being smaller. But your body deserves better than this approach!

Along with your nutrition and supplements, you should follow a comprehensive training program that maximizes fat loss while also minimizing muscle loss. When sustainable weight loss is the goal, muscle is your friend! It burns calories, gives your body shape, and allows you to stay active and feel good doing it.

The most popular weight-loss programs in BodyFit share a common thread: they make you sweat, but also encourage a healthy overall body composition and muscle growth. If you want to stay lean for the long term, you need more than just to "cut!"

5 Popular Weight-Loss Programs:

• Jim Stoppani's 6-Week Shortcut to Shred
• Lee Labrada's 12-Week Lean Body Trainer
• Transformed: 12 Weeks to Your Best Self
• Alpha M's Tailored: 6 Weeks to Living Lean
• FYR: Hannah Eden's 30-Day Fitness Plan

Are Fat Burners Safe?

As long as you take a reasonable approach to your overall nutrition and keep a watch on your stimulant intake, fat burners can be a safe way to increase your results. Here are the biggest rules to keep in mind.

Don't diet forever: To be clear, no, you don't need to be on a diet for the rest of your life to lose weight. As registered nutritionist Paul Salter explains in the article "Your No-BS Guide to Effective Weight Loss," a concise timeframe is the best way to get results.

"If you're serious about losing weight, plan on dieting for 10-14 weeks," Salter writes. "This will give you enough time to fine-tune your diet for your particular food preferences and activity level. If you cheat on your plan occasionally, just get back to it and keep moving forward."

After your diet, and once you cycle off of your fat burner, it's important to bump your calories back up to or above what is known as "maintenance," where your calories and calorie burn are roughly equal. One popular way to do this is what is known as a "reverse diet," where you gradually and systematically raise calories. Registered dietician Katie Coles explains how in her article "The Ultimate Guide to Reverse Dieting."

Don't go too low on calories: During your targeted diet phase, the key is to stay in a slight caloric deficit—that means consuming fewer calories than you burn. But don't think that fewer is always better! It's a common myth of fat loss, particularly among women, that an extreme calorie deficit is a good way to get more out of a fat burner.

"Plenty of diets cut calories seriously low, at least at first, and they get results. But not forever," explains Susan Hewlings, Ph.D., RD, in Bodybuilding.com's Foundations of Fitness Nutrition course. "Past a certain point, restricting calories doesn't predictably lead to weight loss—and if it does, it's in ways that aren't healthy, and it definitely won't feel pleasant or sustainable for you."

Remember, the ultimate goal is feeling good and being healthy, not just looking lean! A good goal to have in mind is to eat the highest amount of calories you can, while still losing some weight.

Be careful with stimulants: If you can't start your day without a cup of coffee and you drink another 3-4 throughout your day, be careful about choosing a stimulant fat burner. Most fat burners, unless they specifically say they are stimulant-free, contain caffeine, yohimbine, or other stimulants.

While you will definitely love the energizing benefits you'd get from such a high caffeine intake, if you're mixing fat burners with multiple cups of coffee or any other caffeine-containing beverage, there is an upper limit for the effectiveness of stimulants—and it's different for everyone.

As nutritionist Alan Flanagan explains in the article "Why Less Sleep Equals More Body Fat," cutting into the quality of your rest—which excessive stimulants definitely can do—can lead directly to more fat gain.

Also, most people who have taken fat burners consistently can tell you at least one story about a time they got more than they bargained for from a single dose and ended up sweaty, jittery, and feeling a little out of sorts.

So before you even get started on your fat burner, make sure to shop around a bit and find the one that best matches your needs and preferences. Read reviews of the most popular fat burners, and don't just jump on the first one you see.

What Is In The Best Fat Burners?

There are two main kinds of fat burners: those containing stimulants, and those which are stimulant-free.

Most (but not all) thermogenic fat burners contain stimulants, usually including caffeine. Caffeinated fat burners are good for people who find it difficult to summon up the energy to do a vigorous workout or lengthy cardio session.

"[Caffeine] helps burn fat, and help athletes do more work for longer periods in the gym and in sport," explains Robert Wildman, Ph.D., RD, in the article "Boost Your Workout with Caffeine."

Caffeine is also a potent appetite suppressant for those who find that their ravenous cravings get in the way of their results. So yes, there's a very good reason that it's such a popular ingredient in fat-burning supplements!

As effective as caffeine is, though, it's far from the only ingredient in popular fat burners. And it becomes even more effective when combined with some of the others.

But to be clear, just because a fat burner has more ingredients doesn't make it better! Especially if you're new to fat burners, focusing on a few essential ingredients like these is a good place to start.

Green Tea: Green tea and green tea extracts have been shown to activate the body's thermogenic fat-burning activity. A study published in the American Journal of Clinical Nutrition found that men who ingested the active ingredient in green tea (catechins) significantly reduced their total fat area, waist circumference, skinfold thickness, and subcutaneous fat area.[2] As exercise physiologist Nick Coker explains in the article "Your Expert Guide to Green Tea," taking this ingredient with caffeine has been shown to make it even more effective.

L‐carnitine: This stimulant-free amino acid has been physique athletes' secret weapon for decades. Taken once or twice daily with food, it can also help your body convert stored body fat into energy, leaving you leaner and more defined. It does this by breaking up fatty acids so the body can use them for fuel. As Jim Stoppani, Ph.D., explains in "Your Expert Guide to L-Carnitine," it has also been shown in studies to support recovery from workouts, reduce muscle damage, and even reduce exercise-induced muscle soreness.

CLA: Conjugated linoleic acid, or CLA, is a naturally occurring fatty acid, similar to an omega-6 fatty acid. Even though CLA is a fat, studies show that consuming 1.4-3.0 grams per day can lead to overall body-fat loss.[3,4] It can also help you retain muscle during periods of weight loss, as kinesiologist Ciaran Fairman, Ph.D., explains in the article "Your Expert Guide to CLA." Remember, muscle is your ally for long-term success!

Yohimbine: This ingredient, made from the bark of the yohimbe tree, is a popular stimulant in fat burners. It has been shown in a well-known study to produce significantly better fat loss results than a placebo among well-trained soccer players.[5] However, more research is definitely needed, and yohimbine isn't for everyone! If you're prone to anxiety or are very sensitive to stimulants, proceed with caution when it comes to yohimbine. Some people find it makes them very jittery or anxious.

Garcinia cambogia: As nutritionist Jonny Bowden, Ph.D., explains in the article "Fat-Loss Hope Or Hype: The Truth About Garcinia Cambogia," this caffeine-free acidic fruit extract has become very popular in recent years. As long as you take it properly, he explains, it can offer potent appetitive-control benefits.

How Do I Know If My Fat Burner Is Working?

Once you find the best fat burner for your goals, give it 2-3 weeks to work before you begin assessing progress or results.

But after that time, definitely track your progress to see how your goals are shaping up! Whether you take progress photos, body-part measurements, body-fat measurements, or just track your weight on a scale, you won't know if a product is helping you see results if you don't know your starting point.

That said, despite what you may think, weighing yourself more often doesn't automatically lead to better weight-loss results, as Paul Salter explains in the article "How Often Should I Weigh Myself?" Your weight is only one part of the story—not the whole story—so don't fixate too heavily on it. How you feel, how you look, and how your workouts are progressing are also crucially important!

Remember, certain people react better to certain ingredients in fat burners, so what works best for one person may not necessarily work best for another. After several weeks, if you find that you aren't seeing the results you had hoped for, consider using a different product instead.

Keep a close eye on your progress over time, stick with your nutrition and training, and use fat burners occasionally for that final 5 percent of results, and see if you can surprise yourself with what you achieve!