This should blow your mind.

2.1 billion dollars are spent every year in America on fat loss supplements¹.

15% of all American adults are trying to use supplements to get an edge in the fat loss game.²

Here is the kicker, some of them don’t work. That means that about 4 Falcon Heavy Rockets or about 10 of those super awesome AT-AT walkers from Star Wars are not being built every year because of money wasted on ineffective supplements.

Clearly this is a giant issue and someone needs to let you know what works and what doesn’t work so we can cut through all the BS, save some money, and actually get results.

1. Iron

I have to come out of the gate swinging here and put this out there before the rest of the list.

Iron is one of the best supplements to help with fat loss. Period. End of story.

Now here is the plot twist.

It isn’t the iron you are thinking of – the kind that comes in the pill. It is the kind that you find in a gym that you have to pick up and put down a lot to help you build muscle. It turns out this type of iron is also one of the best ways to accelerate fat loss.

I mean I spent an entire semester in graduate school reading papers about this. In about every permutation of study design possible, lifting weights helps you lose body fat. Even at a small dose – two sessions a week are enough to speed up body fat loss, even in people with type 2 diabetes³.

So let’s make a deal. Before you even think about moving on down the list, start with your daily dose of iron.

2. Caffeine

Caffeine is one of the most studied supplements on the planet.

It is currently the most well documented legal supplement that acutely increases fat oxidation^4,5,6.

Related: 5 Best Non Stimulant Fat Burning Supplements

Now there are some important things to note about caffeine that we need to fully understand:

1. Much of the fatty acid that is release from fat cells during caffeine ingestion is recycled, in fact only about 25% of what gets released is oxidized.
2. Acute increases in fatty acid oxidation don’t always mean substantial weight loss, in some cases the net result is no weight loss if there isn’t a meaningful calorie deficit.
3. One can very quickly habituate to caffeine, meaning it loses its efficacy and must be cycled on and off of.
4. It can lead to temporary increases in insulin resistance.

Caffeine appears to convey some benefit for fat loss when used acutely⁷; however, over much longer time frames it does not appear to help with long term fat loss or weight maintenance⁸.

So if you are going to use caffeine as an accelerant for fat loss use if for short periods when you REALLY need it (e.g. contest prep) and cycle off it before you need it.

3. Green Tea Extract

This one puzzled me at first. I didn’t quite believe the data but green tea has a small, but noticeable effect on body fat.

Green tea has compounds in it called catechins that can alter metabolism and increase fat loss. In one study, consumption of green tea augmented exercise induced fat loss⁹.

These compounds can be combined with caffeine (our super hero from above) and have been shown to augment the acute metabolic boost that caffeine gives you¹⁰.

Now, drinking green tea is great but you have to drink a lot of green tea to get the same effect as supplements. In fact, you have to drink 4-5 cups of green tea to get the same effect as 300 mg of supplementing with green tea extract.

4. Yohimbe

Yohimbe was originally investigated for its aphrodisiac properties and its use for erectile dysfunction. More recent evidence indicates it may be a moderately effective fat burning supplement.

In a study of young soccer players, yohimbe led to a 2% reduction in body fat in already lean people¹¹. This is a notable finding and indicates it may be a useful supplement for fat loss for active, healthy, lean people.

However, there are some cautionary tales. Yohimbe is known to interact with other pharmaceutical compounds and higher doses may lead to an increase of cardiovascular events. There is the other issue of getting accurate doses of this compound, many yohimbe supplements do not provide the actual dose they claim to provide. Furthermore, there is evidence that it increases anxiety among many people.

This supplement shows promise as a fat burner but more careful, detailed investigations need to be done to tease out the side effects.

5. Synephrine

Synephrine which goes by the very X-MEN like name of citrus uranium can be thought of as the mild, baby brother of ephedrine in that it exhibits many of ephedrine’s qualities, but to a much lower degree.

Synephrine has been shown in increase metabolic rate to a small, but discernible degree in women¹².

Related: How To Choose The Right Supplements According To Science

Synephrine has been shown to increase lipolysis, which is likely one of the primary mechanisms of increasing the metabolic rate observed in the women of the previous study¹³.

While there is potential here, there are no large, randomized controlled trials to determine the extent to which synephrine might be effective and the current thoughts are that it exhibits a minor impact.

The Wrap Up

There are a handful of fat loss supplements that have shown some benefit and might be worth looking into.

The very first stop on the fat burner train is iron, as in the iron you find in the gym. If you aren’t resistant training that is your first move, get started. NOW.

Caffeine and green tea extract also show promise as fat burners. Caffeine needs to be used in short cycles and is only really good in the short term. It is not a good tool for long term fat loss.

Yohimbe also shows some promise amongst lean people but there is a heavy list of side effects to watch out for.

Synephrine may turn out to be a less potent, but minority effective, little brother to ephedrine. More work still needs to be done on synephrine.