Does Coffee Make You Fat?


I just finished reading Why Diet and Exercise Fail…and I am ticked off.

starbucks IV addictTicked off because author Daniel Matthew Korn is making me re-think my morning cup of Gold Coast.

Korn believes that long term caffeine consumption, when combined with a typical Western Diet, is akin to throwing gas on your obesity bonfire.

Or, as Daniel says, “long term caffeine use, in combination with other dietary factors can contribute to lowering our ability to use our stored body-fat and interfere with our storage of nutrients”.

Why would coffee lead to obesity?

Theory #1

  • Long term caffeine use can lead to elevated stress hormones (ie Cortisol)
  • And heightened cortisol levels is associated with obesity

Theory #2

  • Chronically elevated cortisol levels results in increased feelings of hunger
  • And obviously hunger leads to eating and drinking more coffee and eating more food and…

Theory #3

  • Chronic caffeine use may interfere with your sleep patterns
  • And sleep deprivation is associated with obesity

Korn’s Conclusion

Chronic caffeine use contributes to obesity because:

  • it increases your level of stress hormones
  • which messes with your brain chemistry
  • and increases your hunger
  • causing you to eat more crappy processed foods
  • while you lay in bed tossing and turning because you can’t sleep

My Conclusion

As Korn mentions, there is very little research into the direct effect caffeine has on metabolism and obesity.

This leaves his theory open to attack.

I can hear the comments already – Association and/or Correlation is not Causation.

And they are right. Korn is making some assumptions.

And good for him. Out of these assumptions, researchers can design studies to test if caffeine has a direct effect upon obesity.

Until then, you can:

  1. Ignore his caffeine/obesity theory as unproven
  2. Or, test the theory on yourself. Sadly, that is the route I am taking…starting tomorrow.

Note: I will be reviewing the rest of Why Diet and Exercise Fail in an upcoming post.


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  1. I’m taking a caffeine break as well – Those first three days are sluggish.

    Another hunger theory would be that caffeine is a diuretic so adding that effect in people who don’t drink enough water in the first place would cause them to mistake thirst for hunger & eat much more food. Typical caffeine intake is also usually accompanied by an energy drink cocktail or mix at the coffee house which would also explain the weight gain.

    If one stuck with black coffee or caffeine tabs, drank plenty of water, and cycled off occasionally the body fat cons should be outweighed by the pros.

  2. Bah, hocus pocus, mumbo jumbo. I have coffee – black every day. Rachel is right, its the crap people put into coffee that makes it fattening, not the coffee itself. How can something that is 99% water, full of antioxidants all the sudden be making you fat? The new Dunkin’ Donuts in my town is making people fat, not coffee! Hail the roasted bean of the coffee cherry!

  3. Hi,

    I am the author. First, the book is about the various things that can explain what studies have shown predict weight gain. People who gain weight tend to have: high stress levels, sleep problems, excess hunger, poor blood sugar control / high blood sugar, excess inflammation, and high cholesterol. The book then shows the various things in our diet that can be responsible for one or more of these effects. The theory being that if we can find something that has all of these effects on us, it is likely a strong culprit in weight gain.

    Second, the book isn’t claiming that caffeine is the main cause of obesity, that is probably coming in the next review. However, caffeine is a contributor to obesity, and there is a reason why it has been missed. It turns out, that some of us have a gene that alters one of the receptors that caffeine has its effect on. If you have this modified receptor, caffeine doesn’t cause you stress of sleep disturbance. Caffeine has been associated with stress, inflammation, sleep disturbance, increased hunger, and some small increases in LDL cholesterol, however, not what we have seen in the modern age. The next review will likely be about what I consider to be the main factor in weight gain, that can explain all of the above predictors of weight gain.

    Third, the book also uses examples to demonstrate that all of the theories in popular diet books can not explain the prevalence of obesity in the United States. The Inuit eat a diet that is 75% fat but are lean, the rural Thai get 70% of their calories from refined carbohydrates (white rice), but are lean (even those that are physically inactive. This shows that losing weight is not as simple as avoiding fats and refined carbohydrates. There are many more examples in the book. Feel free to post questions directed at me and I will respond.

  4. If fat caused weight gain that the Inuit, who eat 75% of their calories as fat would be obese. Sugar, at least in fruit juice, has not been shown to cause obesity. However, deficiencies in certain nutrients has been shown to increase hunger. The body seems to crave nutrients as well as calories (hence our current state). However, one of the effects of caffeine is to create certain nutrient deficiencies, stress does this as well. So there is a connection between caffeine and nutrition.

  5. Quitting caffeine is not the complete answer. We are drinking caffeine because we aren’t sleeping well and waking up refreshed and energetic. In nature, mammals wake up at sunrise without alarm clock. The next post will likely detail what has changed in the modern diet which explains why we no longer sleep well and feel the need to consume caffeine.

  6. Caffeine is a drug, and a side effect of many drugs is weight gain. This is not uncommon. Anti-depressants, anti-convulsants, anti-psychotics, and more are taken with water and cause weight gain. They will cause weight gain even if you take them with a anti-oxidant vitamins.

  7. Daniel fat does not cause weight gain per se. TOO MUCH fat causes weight gain.
    Italians have one of the lowest obesity rates in Europe and drink a lot more coffee than the British who have one of the highest.
    I agree there is a connection between caffiene and nutrition but there is no way it is to blame for the amount of fat Scottish people I know who only drink tea and the thin Italian and Spanish people I know who only drink coffee.

  8. Rachel,

    This is in response to your post below. It would not let me reply directly to it.

    1.) Caffeine – Unfortunately, we can not compare the population of Britain to Italy because there is a gene that alters our response to caffeine. We do not know what the prevalence of that gene is in the British or Italian populations. The people who do not have the stress or sleep disturbance response to caffeine are the ones who drink it the most. In studies of caffeine consumption versus weight, the people who drink the medium amount of caffeine are the thinnest, while the lowest and highest consumers of caffeine weight more. This is probably because drinking a small amount has only a little effect, and drinking a large amount indicates you have a gene that offers protection.

    2.) Too much fat causes obesity – this does not appear to be the case for all types of fat. If the Inuit can eat 75% of their calories from fat, certain that would pass the threshold of too much fat. Americans are getting 30% of their calories from fat, but are more overweight than the Inuit. The French are eating more saturated fat than Americans bu they weight less and have less heart disease. On the other hand, the Thai eat less fat and more refined carbohydrates than Americans and are thinner. Obesity does not appear to be as simple as fat or carbohydrate consumption. The nutritional make up of those fats and carbohydrates can not be ignored.

  9. I quit coffee four months ago. 30 years of searing abdonimanl and anal pain disappeared within a day.

    That is all I have to say on the subject.

  10. I have one cup a day, in the morning, black—super strong. I recently lost 20lbs and I think it’s actually helped because the caffeine A) boosts my focus therefore, I forget about snacking. B) I’m also asthmatic and it helps my breathing.

    I agree though, I think that all of the sugar and whole milk/half and half that folks gash in their coffee is what is killing their diet. No one usually takes liquids into consideration when watching calories–lay off the sugar/milk and alcohol and you will see your waistline deteriorate and health progress.

    I have used Personal Trainers, fad diets, pills, you name it in the past (I’ve never been overweight per say, but not healthy) and all have failed. For the past 3 months I’ve lost 20lbs by simply watching what I eat (as nature intended) and exercising. It’s as simple as that. My lifestyle has changed for the good—–but coming to a close, I won’t give up that cup of joe in the morning—it’s all about moderation.

  11. If coffee makes you fat, why do body builders include it in their “leaning up” diet before competitions? Coffee has been proven to speed up metabolism- thats why!

    Guys, coffee will NOT make you FAT. Eating more calories than you burn will make you fat.

    Excluding or restricting coffee, alcohol; or whatever else for that matter; is not the magic bullet everyone is looking for to lose weight and keep it off.

    At the end of the day it is about calories. Burn more calories than you consume, and you will lose weight.

    Then when you start losing weight, focus on trying to build up some lean (not bulk!) muscle. This, combimed with cardio, and are healthy eating plan and you will achieve your goals.

    Notice I said healthy eating plan? ( think and call it a “diet” is setting yourself up to fail)

  12. Very interesting – I’ve actually given up coffee inadvertently for the past two or so weeks and been drinking black tea with spices for my morning beverage. I don’t know that it at all connected to my weight loss because I have also completely overhauled the rest of my diet, but I have lost five pounds in the past ten days.

  13. I think all the crap (sugar, cream, etc.) that people are adding to their coffee is adding to their waistline, causing obesity. And of course, the garbage that people eat, thinking it’s real food, is effecting their weight.

  14. I think you’re overlooking something rather glaringly obvious. There ARE research studies into the effect on weight loss from use of moderate caffeine consumption. The science is in, it acts on increasing thermogenesis, it’s a diuretic and it has certain appetite suppressing characteristics. Now that said do you go out and cram 10 gallons in every morning? Well gee there might be trade offs to that.

    Moderate consumption of coffee (without a ton of sugar or cream) MAY lead to increased weight loss results.

  15. Hi! I have an under-active thyroid and coffee doesn’t benefit your endocrine system. The endocrynologist (hope thats the correct English, my home language is Afrikaans) told me so and I read it in Mary-Ann Shearer’s book, both good sources. I’ve stoped, started again, etc. Now 3 weeks without coffee again. I’ve always had coffee without sugar, with some 2%milk, still like the taste! But for my weight it’s really better without it. Even on one cup a day you’re addicted and will have withdrawl-headaches. Don’t stop suddenly, wean yourself off it: reduce the number of cups gradually to 1 per day, keep there for a week, reduce to half a cup per day for a few days… Good luck!

  16. I imagine we also need to ask ourselves why chronic caffeine users are in need of it, or perhaps why they started using it to begin with. If we took caffeine out of a coffee drinkers life (and for the purposes of this discussion, we are removing it without withdrawal), and that person couldn’t find the energy to get through a day or a workout, this may indicate poorly managed stress or unhealthy sleep patterns. The lack of energy could also be symptomatic of hormonal imbalance, which is obviously corrected by diet, exercise, and in certain cases, medical intervention. Caffeine may have been a band-aid for a greater concern.

    In the case of bodybuilders, I can only add that my personal trainer is a competitive bodybuilder and he agrees that that famous “aspirin-caffeine” pre-workout stack works for some and simply is to much of a diuretic to build large muscles for others. He tried it for a long time and his muscles couldn’t develop beyond a certain size, so he chose to stop and has seen growth.

  17. Can’t believe you people are seriously discussing a Nu-Metal band’s drunken ravings about obesity? -pft- The internet!

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