Do “Fat Burner” Pills and Thermogenics really work?

The reviews on Amazon are good! The ingredients look safe! The people who use them claim they really do make the scale move! How do they work? And DO they work? The answer might surprise you..

Let’s take a close look at most common ingredient found in most thermogenics (and in fact, the secret ingredient to almost all “fat burner” pills): Caffeine

Caffeine is probably the most powerful thermogenic we have, and taking caffeine in extremely high doses does, in fact, make the scale move. But before we declare fat-burner pills a miracle weight loss formula, let’s examine how they work:


Your heart rate goes up

The increase in heart-rate that accompanies the use of stimulants definitely simultaneously increases your metabolism.. albeit slightly. (About 20 calories per hour difference can be measured with a heavy dose).  Note there is a subsequent crash after the caffeine wears off, where your heart-rate drops slightly lower than normal, which arguably offsets any extra calorie burn you got at the beginning, but let’s ignore that and assume NO crash after the effects wear off — just for fun.

Your core body temperature goes up

This is the core reason people claim that thermogenics and “fat burners” make the scale move. Caffeine (and similar stimulants) absolutely will increase your core body temperature, which also absolutely DOES increase your metabolism slightly. (Again, about 20 calories per hour difference can be measured with a heavy dose).
But there’s an interesting side-effect to increasing your core body-temperature… Your body starts dumping water. (This is why people with high-fevers become severely dehydrated). As your core temperature increases, your body starts ejecting water. Lots of it. And THIS is why most people think “fat burner” pills work… their core body temperature goes up.. their body dumps water… the scale moves IMMEDIATELY.  (“omg.. I took this pill and I started dropping weight like crazy!!”)..
Of course, your body only has about 10 to 15lbs of water-weight that it can safely get rid of before you hit dangerous hydration levels, and this creates a dangerous cycle.
  • Day 1: I lost 2lbs!!!
  • Day 2: I lost another 2lbs!!!
  • Day 3: I lost ANOTHER pound!!!
  • Day 4: I lost 2lbs!!!
  • Day 5: I lost a pound!!!
  • Day 6: I lost a pound!!!  I can’t believe I lost 10lbs! These pills are amazing!!!!!
  • Day 7: I lost nothing… I don’t feel well.
  • Day 8: I lost nothing.. I don’t feel well.
  • Day 9: I lost nothing.. I don’t feel well.
  • Day 10: I lost nothing.. I don’t feel well.
  • Day 11: These stupid pills stopped working. I’m going to stop taking them.
  • Day 12: Ugh.. I gained 2lbs!
  • Day 13: I gained 2 MORE lbs! OH NO!

… Wash, rinse, repeat… and the industry sells more and more pills while YOU destroy your liver and your metabolism.

Yeah, but these things actually increase the metabolism, right?

Yes they do! Kind of..
Let’s say you take a monster boost of caffeine (~200mg) and you can get an extra FIFTY calories of metabolic boost, per hour, while the caffeine is in full effect (probably around 2 hours).   That’s a BOOST of 100 calories PER from the thermogenic.
Do it twice a day (and now we’re at the FDA-approved limit for daily caffeine) and you’ve earned 200 calories PER DAY from pumping yourself full of caffeine, to the maximum allowed by medical science. 200 calories a day ain’t bad!!
Now, remember, it takes 3500 calories to burn 1lb of fat…  So if we crunch those numbers real quick (200 calorie per day boost… 3500 calories needed to burn 1lb of fat)… we find that if you pump yourself FULL of stims, you can expect an extra 1.5lbs per month of weight loss.  Who wouldn’t take that?!

But there’s a dark side…

It only takes about 30 days to gain a 100% tolerance / addiction to caffeine… So at the end of 30 days, the weight loss STOPS because the 400mg of caffeine you’re taking is no longer having any real effect. (In fact, without it, your metabolism now grinds to a complete halt)….  And now, JUST to maintain a NORMAL functioning metabolism, you need 400mg of caffeine every single day.
Your metabolism is now addicted to caffeine, and can’t function without it.


In the short term (<30 days)?  Thermogenics could theoretically boost your metabolism to the net of 1.5lbs per month of additional weight loss.  In the long-term (>30 days)… Thermogenics will WRECK your metabolism.
Put another way.. they’re a TERRIBLE IDEA for burning fat!

So are stimulants always bad?

I’m a big fan of the use of thermogenics immediately prior to heavy workout, because studies show that if you’re pushing you heart-rate into 150s and 160s for an extended period of time (1+ hours) while on stimulants, the metabolic reversal effects are minimized and the caffeine is probably a net positive!  This is why pre-workouts are LOADED with stims.
In other words — combine the stim with HIIT training where your heart-rate is pushing its limit for long period of time, and caffeine isn’t so bad!
Otherwise? Stay far, far away from any pill that claims to “target belly fat”,  “burn fat”,  or act as a “thermogenic”.