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Does Caffeine Make You Fat?

Ok guys, this is IMPORTANT!

No matter what diet your on, if your guzzling coffee like it’s going out of fashion, you may be working against yourself!

There is still no definitive answer to this question but I have recently come to my own conclusions on the matter. It could have a DRAMATIC implications for your diet, and could help you reach your goals FASTER.

So, why the confusion?

Some people say that caffeine will raise your blood sugar, others say it doesn’t. Some studies show that it does, BUT, only in diabetics.

So, what’s the truth??

A lot of you will remember that a I gave up all caffeine a short time ago (except for 100mg pre-workout) and felt much better for it. Yes, there were the initial caffeine withdrawal headaches but I got through it and really felt GREAT afterwards.

This prompted me to look into caffeine again and see is it negatively impacting us in terms of weight control.

The basic question is….

Does Caffeine Raise Blood Sugar?

If so, it therefore raises insulin and we know that insulin spikes store fat.

To answer that question we need to look at STRESS. In our caveman past, stress (possibly in the form of the threat of being eaten!) served us well in that it stimulated the adrenal glands to release the hormones dopamine and adrenalin.

These hormones seek to get any stored glucose back into the blood stream to be used as quick energy. More glucose in the bloodsteam means more insulin.

Here’s the important part – Caffeine ALSO stimulates the adrenal glands to release dopamine and adrenalin.

From this we could logically infer that caffeine will raise blood sugar and can contribute to fat accumulation.

It should also become apparent that stress is a bad boy. Being stressed out will have similar effects to guzzling coffee in terms of blood sugar and insulin. Also, as I state in point 7 in this article, stress is catabolic and works to break down muscle tissue.

For those of you on my Total Six Pack Abs program, the recommendation is clear: Ditch the caffeine.

One exception; you’ll remember from the book that I state that caffeine DOES enhance the fat-burning effects of ephedrine. Towards the end of a cutting cycle in an effort to help lose those last couple of pounds of fat, an EC stack will work wonders. Just remember to come off it altogether when you’re all done cutting.

I will still be taking my 100mg caffeine anhydrous before workouts as any extra glucose dumped into my bloodstream will be readily used up by intense THT workouts.

So there you have it folks. For the most part caffeine is a bad boy, but still has its uses.


Your buddy,


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Mark McManus
Mark McManus
Mark is now available for 1-on-1 consultations to help you take your results to the next level. Click here for more details.
Mark McManus is a trainer & author from Ireland. His work has been featured in major publications all over the world. He is the creator of the free growth-promoting workout Targeted Hypertrophy Training' (THT) and author of the NEW fat-torching system Total Six Pack Abs.
He has also created the BREAKTHROUGH arm and chest maximizer programs The Arms Blast' and 'Chest Blast' workouts.
And if you're a fan of delicious high-protein recipes to fuel your muscle growth, check out his cook book 'Buff Baking' here.

Comments on this entry are closed.

  • Jamie May 25, 2009, 8:46 pm

    Thanks for the great info mark. I’ve already cut down based on your last article on caffeine.
    Thanks for all your work!

  • John May 25, 2009, 8:46 pm

    Too bad… I love my coffee. I cut back to two cups a day. I have eliminated so much else — sugar, carbs etc.

  • Sean May 25, 2009, 9:07 pm

    Very interesting Mark, thanks for the post. I always assumed that caffeine would boost metabolism, causing more fat loss. Damn glucose.

  • Mark McManus May 25, 2009, 10:24 pm

    @Sean. Yes it does boost metabolism but there are better ways to go about that.
    @Nico. No worries, there are plenty of opinions on this topic. Yes glucagon’s job is to raise blood sugar, but it won’t raise it to higher than normal levels. It’s there to make sure blood sugar doesn’t drop too low.
    Yes, the glucose will be taken from storage i.e. liver glycogen.
    Also, you make a good point about caffeine taken with food. I actually read a study on that recently but didn’t bookmark it unfortunately. It stated that caffeine taken before a meal would increase the blood sugar and insulin response more than the meal would itself. Thanks for your input.
    @Antonio. I love green tea. It has many health benefits but I think the weight loss claims are out of proportion. The only weight loss supplement that is sure to help is ephedrine. Even then I would only take it at the tail-end of a cut.

  • Nicolas B May 25, 2009, 9:30 pm

    Hey Mark,
    I love how you always try to get to the bottom of things but I am not sure you got this one right. I am currently in medical school, here are a few points I want to make:

    – while insulin is bad, raising the blood sugar is not necessarily. Think about it: insulin’s goal is to lower your blood sugar, therefore something that does the opposite could be good. Think of glucagon (the opposite of insulin), glucagon raises your blood sugar while not increasing your fat.

    – furthermore if increasing your blood sugar was bad, then exercising would be bad (check it out, exercise raises blood sugar). If we do not increase our blood sugar when we exercise, we would pass out.

    – the mistake you might be making is thinking that high blood sugar with caffeine is the same that the one that leads to insulin increase. The thing is that you are not thinking about where this sugar is coming from. When you take coffee, you are not (at least I am not) eating at the same time, therefore to raise the sugar, the body must take it from somewhere. Where? (hint: Fat or glycogen storage!!!)

    Mark, I think that you are very intelligent person, so I tried to write an intelligent answer. There are plenty of things wrong about caffeine, I just do not think that fat gain is one of them

    Continue the good work, Nico

  • Antonio Wright May 25, 2009, 9:34 pm

    Another great article! So, what are thoughts on Green Tea?

  • Antonio Wright May 25, 2009, 10:34 pm

    Mark, just for clarification. Would you take the Green Tea or the ephedrine at the tail-end of a cut?

  • Mark McManus May 25, 2009, 10:37 pm

    @Antonio. I meant the ephedrine, sorry ’bout the confusion.

  • Darrin_lean_muscle May 25, 2009, 11:33 pm

    I also have kicked the caffeine habit, though for different reasons (http://worldfitnessnetwork.com/2009/05/kick-caffeine-addiction-with-intense-weight-training/ ).

    I read something recently about green tea possibly having fat-storing side effects. Any truth to that?

  • dave May 26, 2009, 1:02 am

    uh, i do NOT agree with this at all- first of all, correlation does not equal causation – that’s rule numero uno in any such analysis…the facts and assumptions here are a bit baseless and an attempt to connect the dots at a broad level is a tough one…

    with that said, i’d suggest isolating the caffeine issue by weight class, as i do believe it may have more of an impact on high body fat types trying to lose weight, though more likely in terms of sabotaging appetite which may lead to binge eating out of caffeine load cycles, less to do with how the body metabolizes caffeine

    at any rate, i’m 5’7, 152lbs and am quite lean, work out very regularly 3x a week on a reasonably serious diet which includes normal crap (because that’s how i roll 😉 – but note this: i drink an excessive amount of caffeine, at least one full pot of coffee every day, sometimes two, and all the way into the late evening or night !! it has had zero impact on my body’s way of storing fat (i don’t seem to hold on to much weight, it’s quite the opposite, find myself loading up on turkey, tuna and meat to get protein overload and milk for fat)…only thing i notice is that it suppresses my appetite and so i must remember to eat in the mornings!! that’s what i’m talking about with the weight gain issue- may be a more interesting angle to explore or research…

  • Space May 26, 2009, 9:03 am

    Hey Mark,
    Intersting analysis but a bit short compared to other proposals you’ve made. I’m still not convinced.

    OK, coffee may raise blood sugar.
    That could mean for me that I won’t be using fat as energy for the next 2-3 hours.
    But I cannot understand how I would start STORING fat just from 300ml of water with two spoons of coffee (no added sugar ofcourse).

    I guess it is possible if you eat cookies or a lot of fat at the same time as drinking coffee that the Sugar coming from coffee ingestion is used as energy and all the rest is finaly stored as fat. But that’s not how I drink coffee.

    Moreover, cafeine raises the metabolism : so if you drink black coffee, isn’t the higher blood sugar compensated/balanced by the higher metabolism ? I’m personnally convinced about that!

    I think you could wright a big article on that subject !)
    Keep it up !

  • Alexi May 26, 2009, 9:56 am

    I would also like to start by saying nearly everything i see here on this site has been VERY useful and i would like to start by saying big thanks to Mark !!!

    but.. im afraid i would have to disagree with this article, even at A level biology you learn that caffeines main metabolic product Paraxanthine (84% of caffeince metabolized to this)has the actual affect of INCREASING lypolysis (fat burning) by freein up triglycerides into fatty acids and glycerol. Ive actually learnt that athletes on caffeine supplements will turn to fat at a greater proportion then those not on caffeine supplement.

    Also, regarding blood sugar i dont think ive ever seen anything regarding this being an issue for any non type 2 diabetes person, but to be honest i feel really bad for type 2 sufferers as they are pretty much warned not to do anything, im suprised they havent been advised to stop ingesting air yet.. the only scientific property of caffeine affecting glucose in blood is the other metabolic product when caffeine is metabolized, theobromine. This is a Cyclic adenosine monophosphate (cAMP) phosphodiesterase inhibitor and this is actually great as it means cAMP (which is used as a REGULATORY secondary messenger) can work UNHINDERED shuttling both adrenaline but also glucagon more effectively round the body and in some one who can produce insulin, this effect will simply make them more sensitive to changes in environment, so ideal and most effective pre workout but no effect really at any other time.

    Caffeine is addictive however, overuse can cause insomnia, nervousness and a whole host of problems, so moderation and correct timing seem to be key with caffeine!


  • Space May 28, 2009, 2:12 pm

    Thanks Alexi for supporting my abstract analysis by scientific facts.
    I would like to add one personal physical observation : I practice some intermitent fasting (usually two days after a hard workout) by skipping breakfast and drinking just black coffee puts my abs at their best visible condition, a real difference compared to when I.F. without black coffee.

    Anyway as Mark and Alexi say moderation is the key as always!

  • Sean May 28, 2009, 3:36 pm


    Keep in mind caffeine is a diuretic, and when you have less water you’re going to look more ripped (even if you’re a bit weaker).

  • Mark McManus May 28, 2009, 8:26 pm

    Firstly, as I state in the article, the definitive science isn’t in. Study results vary depending on
    The amount of people involved,
    Health of those people,
    Who funds the research (important)
    What I’m doing with this article is sharing my opinion thus far.
    A Dutch study found that just 1 shot of caffeine raises adrenalin fivefold and decreased insulin sensitivity by 15%.
    Like stress, caffeine causes the adrenal glands to release hormones that will take stored glucose back into the bloodstream.
    The pancreas will then release insulin to deal with this extra blood sugar.
    One concern is that excessive caffeine consumption can cause you to become less and less sensitive to insulin and promote insulin resistance. Patrick Holford, the guy that I’m currently researching regarding an all-new GLAD diet, talks about this a lot in his books.
    Insulin resistance is a definite cause of obesity IMO, as you’re more likely to turn glucose into fat, not to mention diabetes & heart disease.
    Yes, it will speed up metabolism but the reason your metabolism and energy levels are low in the first place is due to blood sugar highs and lows fueled by inferior nutrition. I would advise people to get their diet in order, stabilize blood sugar and soon you won’t need a temporary hit from a stimulant.
    Anyway, the temporary ‘hit’ from the adrenalin and increased blood sugar wears off; you feel lousy and need another hit. If you keep giving in to the craving you end up where I was – dependent on caffeine just to get through the day.
    Remember, stimulants are addictive – I’m speaking from experience. At its worst, I was even waking up tired. I’m glad those days are over!
    I say…
    Keep your blood sugar stable with diet,
    Drop the stimulants (for the most part, the odd cup is fine)
    Ensure you’re not overworking the pancreas and becoming insulin resistant, thereby storing more fat and burning less of it over the long-term.

  • Alexi May 28, 2009, 8:48 pm

    I definitely agree with the addictiveness of caffeine, not worth it, good diet is an essential thing to master as a life skill, the more supplemntation the more likely you will loose control of your goals when you dont have the supplements, i guess you have to sit down and think about how realistic the life style your living is long term, can you see yourself being dependant on caffeine for ever? :) i completely agree with mark on that

  • Matt May 29, 2009, 4:27 pm

    I dunno if caffeine necessarily makes you fat, but from personal experience, it can keep you at a plateau. I just did a month of near-ZC and 2-3 cups of black coffee and the scale didn’t budge. Granted I’m 6’4 215 with less than 15% BF so getting the last few off is going to be a struggle anyway, but for now, I’m dropping the java.

  • Nick May 31, 2009, 2:40 pm

    Great article – I have always wondered what the implications of drinking coffee in excess could be as far as building muscle and burning fat, but I have never researched the topic. Probably because I didn’t really want to know the truth!

  • Dan June 5, 2009, 11:50 pm

    Well that’s kind of bad news, man. I have experimented with and without caffeine in my years and I find that drinking 12-16 oz of coffee a day increases my productivity at work by about 25%! I am in sales and it helps me think on my feet quicker and prevents brain fatigue during my 12 hour day. If I just bang my wife maybe for an EXTRA 20 minutes a day, do you think that will be enough to compensate for the caffine intake? I already do this when I drink alcohol (ie. 5 minutes for each beer) so I am wondering if the same would work for coffee.

    Thanks and love your site!

  • Mark McManus June 7, 2009, 5:48 pm

    @Dan. I’d personally opt for the sex. Calories burned and more fun :)

  • juice September 20, 2009, 6:26 am

    caffeine is fantastic for your health at anywhere from 100-300 mg a day. this does not mean from soda or chocolate. but Japanese green tea is the purist and most abundant source for the effect you wish to obtain.