Calories or Insulin: Which is Worse for the Waistline?

By Mike Howard

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Control calories or control insulin… or both? Which is more important when it comes to battling extra pounds? Hint… there’s no simple answer.

If you’ve read any diet book released in the past 5-10 years, you are probably convinced that excess calories are off the hook and the insulin is the devil when it comes to packing on the pounds.
Now being that we are hard-wired to like simplicity, the idea that insulin makes us fat; carbs drive insulin and therefore we just quell the insulin by cutting out carbs and voila – The body we’ve always wanted. Here are some snippets regarding insulin and calories and their roles in fat storage.

  • Insulin has many roles, including the ability store fat under certain conditions. To label insulin as the “fat storage hormone”, however would be an oversimplification.
  • Insulin does not appear to directly cause fat gain under low calorie conditions
  • Lower insulin response to a meal surprisingly does not consistently correlate with greater satiety.
  • Reasonably cutting calories improves insulin metabolism over a wide range of carbohydrate levels. Also, insulin levels decrease with decreases in body weight regardless of calorie composition.
  • Glycemic index studies are conflicting with the Cochrane Collaboration concluding low GI diets to be effective, there are other studies that don’t show any difference in body fat or satiety when calories are equal.

So is cutting calories the answer? Not so fast…

  • Calories in vs. calories out doesn’t work out so cleanly for many people.
  • Scads of individuals have succeeded by cutting carbs instead of calories. No “metabolic advantage” of lower carb diets has been proven, however in tightly controlled clinical trials.
  • Creating a caloric deficit is necessary for long term fat loss, BUT there are smart and not-so-smart strategies as to how to achieve this.
  • Cutting calories too low can suppress the metabolism by forcing the body into a “conservation” mode – fluctuating hormones that retain body fat.

Is there a case for both?

  • Many people have found success on low glycemic index/load and otherwise carb-controlled diets. Eating lower glycemic index and keeping refined grains to a minimum is a good idea in spite of the inconclusive data relating to their long term effectiveness in controlling weight.
  • Even while low carbing, however, calories can and do matter at some point in the weight loss journey.
  • Insulin, blood sugar and calories aside, eating foods higher in nutrients is never a bad idea and these are typically found in low glycemic foods.

So instead of being hung up on whether insulin resistance causes overeating or the other way around, just focus on making good choices one meal at a time.


  • Bowen J, Noakes M, Clifton PM. Appetite hormones and energy intake in obese men after consumption of fructose, glucose and whey protein beverages. Int J Obes (Lond). 2007 Nov;31(11):1696-703. Epub 2007 Jun 26
  • Akhavan T, Anderson GH. Effects of glucose-to-fructose ratios in solutions on subjective satiety, food intake, and satiety hormones in young men. Am J Clin Nutr. 2007 Nov;86(5):1354-63.
  • Friedman MR, et al. Popular Diets: a scientific review. Obes. REs. 2001. Mar; 9 supple.
  • McLaughlan T et. al. Differences in insulin resistance do not predict weight loss in response to hypocaloric diets in healthy obese women. J. Clin Endocrinol Metab. 1999.


  1. Charles

    I agree with Dr. Steve, this is a well written and balanced article. If every nutritionist presented their knowledge in a balanced way consumers would be less confused.

    By the way, hormones and enzymes and not calories control all of our biochemical processes including weight regulation.

    So I don’t care about the calories in food as much as I care about the effect the food will have on all our hormones.

    Hormones are the most important factor in weight control, and I hope the nutrition world starts talking more about hormones and less about calories.

  2. Ed

    16 months ago, I realized that salt, MSG and sugar are added to foods as flavor enhancers – enhancers that do a good job of tricking us in to eating too much. Here is a simple test you can do yourself – go to your local megamart and buy a popular brand of “vegetable thins crackers” (or similar) (containing MSG and a host of flavor additives). Go to your local health food store and buy a similar organic, no artificial flavorings vegetable cracker. One has an intense flavor that literally erupts in your mouth – and you can’t eat just one. In fact, you’ll quickly down a handful. Now eat the other with out the flavor “drugs”-the taste is subtle but good. And its easy to stop eating after 1 or 3 or what ever you choose. Food companies are in the business of selling more food – and they are in an arms race to create manufactured “foods” with ever more intense flavorings to satisfy and encourage more consumption. I suspect low GI (and other approaches) may work simply be eating real food instead of “flavor enhanced foods”. Inspite of a very weird year for me, I’ve lost 22 pounds in 16 months eating primarily a low GI diet. My appetite decreased significantly over this time such that over eating is no longer an issue. And today, I’d much rather eat real food than “flavor enhanced” junk sold as “low fat” or whatever in the local megamart.

  3. Mike H.

    Great points, muata! and congratulations on your awesome transformation! I’m a big fan of AC’s, BTW.

  4. Danielle

    Anytime I counted calories, I gained weight. Once I cut my carbs and lowered my blood glucose/insulin levels, I lost weight without effort. One pound a week comes off and that was even before I exercised. Good Calories, Bad Calories by Gary Taubes is a wonderful book.

  5. Muata

    A calorie is a calorie; however, how the body uses it depends on its state: just getting up, during exercise, after exercise, 4 or more hours after excercise, etc. What I’ve learned over my 5 year journey of reducing my body fat percentage from 44% to under 10% is that many of us truly don’t understand how the body gains and loses weight from a cellular stand point, so we are confused by all the mis-leading and hyped-up marketing in the diet and fitness industry. For instance, the Glycemic Index is a major bust because it was developed using 50g or a particular food, by itself, to determine its rating. In the real world, no one sits down and eats just 50g of lentils by itself, waits for it to be digested, and then move on to their next 50g of food! Also, anyone who still believes that calories don’t count clearly don’t understand that the second law of thermodynamics is a scientific “law” for a reason–there’s been no metabolic or tightly controlled study that disputes it! Now, this does not mean that everything works out as neatly as the formulas our trainers or dietitians use or that everyone will lose at the same rate; however, the fact that you gain weight when you have a surplus of energy and you lose weight when have a deficit is refutable. A calorie is a calorie, but how many nutrients are in the calorie you’re eating is what we really need to be focused on …

  6. Tom

    I disagree with the calorie theory. A calorie is a unit of measure, like a gallon. Food is made of 3 basic stuffs, fat, carb, and protein. These stuffs have different effects on the body. You put gallons of gas in your car, but what if you put gallons of milk in it? A gallon is not a gallon, just as a calorie is not a calorie. Someone eating a diet of 2000 cals of brocolli and tuna, will drop body fat like crazy. But what if an obese person just ate 2000 calories a day of cupcakes and candybars? Foods are different and affect the body, brain included differently. It’s all about calories at all.

  7. SueK24

    Great info in this article!

    To add to it, eating with the focus on insulin control usually results in a calorie restricted diet without having to pay attention to counting calories. One acheives insulin control at lower levels by eating a moderate amount of lower glycemic index and glycemic load carbohydrates, a sufficient moderate amount of low fat protien, and a little monounsaturated fat. This is inherently a calorie restriced way of eating. It is the basis of the Zone diet and lifestlye. The Zone is a simple, well-balanced, clinically proven anti-inflammatory lifestyle that can help you lose excess weight and keep it off forever. It fights the effects of aging, reduces the risk of chronic disorders and improves physical and mental performance.

    Calorie restiction can be practiced without paying attention to insulin control, but when the focus is placed on insulin control, calorie restriction will go hand in hand without the need to pay attention to calories.

  8. p/f

    It’s not just about weight though.

    There was not one overweight person on my mother’s side of the family – all of them were eating what I’d say was a low calorie diet that consisted of primarily high glycemic-index foods and higher than average consumption of alcohol (those English!). EVERY ONE of the eight siblings who survived into adulthood has developed Type II Diabetes, some got the added benefit of organ failure or Dementia.

    I don’t think that everyone who eats (and drinks)like this will be Diabetic, but if you ‘win’ the genetic lottery – there is going to be trouble – fat or not.

  9. Barry

    Of course there’s a simple answer: Calories.

    If you are not eating a surplus of calories you will not gain any fat.

    Period, end of story.

  10. Cari

    Ben, I’m not a dietician but I think there are very few foods occurring naturally that don’t have carbs in them either. Like I say, it’s an interesting book – and I think it raises some thought provoking arguments, but it sure left me with almost as many questions as answers. They have some explanations that (from my limited experience of biology make absolute sense) and then there are others that really make me go huh?

  11. Anita

    I like the way you’ve presented this, Mike… The bottom line I believe is balance. Balance between the amount of calories, and the types of foods that we take in at each meal.

    I don’t believe you can choose to do just low cals without watching the nutritional composition, and you can’t choose something with a favorable glycemic index and then eat a ton of it.

    I’m a great believer in smaller more frequent meals, that way you can achieve both. Also, I get bored of the same foods all the time, so having smaller meals allows me to have the variety and not overeat on any one thing.

  12. Spectra

    I’ve never really watched my carb intake, but I do watch my total calorie intake. I tend to believe that exercise has more of an impact on insulin resistance than simply following a low GI diet. Exercise boosts the amount of insulin receptors in your cells, making you less likely to develop insulin resistance. I suppose eating a low-GI diet can’t really hurt, since most low-GI foods are also fairly low in calories. But I’m still sticking to my theory that eating a varied diet that’s fairly low in calories and getting regular exercise is the best way to not get diabetes later in life.

  13. Ben

    Even if true, how is this useful? There’s no diet that has zero carb calories.

    If you use 2000 Calories and take in 2100 Calories, how can you lose weight? It seems like you’re saying that you won’t gain any weight if all 2100 are fat or protein — fine I guess. But what if 2000 of the 2100 Calories are fat and protein and 100 are carbs? It seems like you stand to gain the same amount of weight as if all 2100 are carbs — 100 Calories worth (about 1/35th of a pound).

    I endorse low-carbs and low glycemic index foods for lots of reasons. But losing weight is essentially a function of eating less (and exercising more). And Calories are the meaningful units of measure for “less” (food) and “more” (exercise).

  14. kb

    can you provide some kind of evidence for this? all food is broken down and the energy in the chemical bonds is released. so, what exactly makes some energy impossible to store?

  15. Steve Parker, M.D.

    Mike, I appreciate your balanced and evidence-based viewpoint.


  16. Cari

    I’ve recently re-read ‘Lights Out’ by 2 medical researchers at the Sansum Medical Research Institute which specializes in obesity… (and while I can’t buy all their theories), I think they make a pretty compelling case that carbs are the only food form that can actually be stored as fat. They make the point that because of the biological pathway that proteins and fats take, it is not possible for them to be stored at fat.

    However, having said that I have to say that, while I have no doubt that they understand the workings of hormones and the digestive breakdown of food way better than I ever will – there books leaves me with almost as many questions as answers.

    For me personally – my biggest single eating guideline is that it is as close to nature as possible. I figure that Nature knows best.

  17. Kami Gray

    I don’t know anyone who would say that “excess calories are off the hook.” Just because some of us whole-heartedly believe that the culprit is insulin doesn’t mean we also think it’s possible to lose or maintain weight without watching or restricting calories. Common sense and twenty years of effortlessly maintaining my weight by limiting calories AND keeping my insulin levels low tells me I’m on the right track. Dr. Barbara Berkely is a board certified internist who has specialized in the care of overweight and obese patients since 1988. Her blog post on is definitely worth checking out…

  18. Sabs

    I am of the opinion that both should be followed. Eating low GI food ensures stable blood sugar, but it does not take the “quality” of food (fat content, etc) into consideration.