The Clean Eating Myth; Why Insulin Isn’t the Bad Guy

Article written by Elliot Atwell

When Brandon Morrison, resident Lift Big Eat Big stone loading expert and member of the badass beard club, asked me to write an article on the myth of “clean eating”, I was sorely tempted to take sides, rally my research, and pit we strength athletes against the aesthetes in a glorious battle of beards, bacon and barbells versus spray tans, spinach and speedos; and let’s face it, with all the modern day Vikings there are in strength sports, we’d win. However, this is my first foray into nutrition journalism, and as much as I want to completely demolish the myth that is “clean eating”, I thought it would be best to cut the sensationalism and actually give clean eating its day in court. In addition, I’d like to address what in my view is the biggest misconception that I currently see in both strength sports and the fitness world at large; which is the role of insulin in fat storage and metabolism.

Clean Eating vs Flexible Dieting

Now, before I go on, let’s at least define ‘clean eating’ in general terms as it is most commonly used, as well as the alternative known as ‘flexible dieting’. At its most basic, ‘clean eating’ involves limiting oneself to a specific set of foods, based on their macronutrient profile and/or their level of processing and refinement. Flexible dieting, on the other hand does not limit the types of food one can eat, but restricts the quantity of foods based on one’s individual body composition, training, and energy demand.

There are so many misconceptions about flexible dieting; often you will hear flexible dieting referred to as ‘If It Fits Your Macros’ or ‘IIFYM’. This is a bit of a misnomer as IIFYM isn’t a diet; it is a protocol within flexible dieting. It’s a response to questions like “can I eat cake, ice cream, pizza etc. and still lose fat” and the response is always “yes, if it fits your macros”. It is a limiting protocol, not a copout to consume large amounts of calorie dense, processed foods. Flexible dieting is all about eating in moderation; being able to enjoy the foods you like to eat, without compromising one’s health or one’s macronutrient goals for the day.

The way I see it, if you can’t enjoy some pizza during a big football game,dinner at a nice restaurant or grandma’s apple pie during the Holidays, there’s a serious problem there, especially if strength sports or bodybuilding are nothing more than a hobby (which is the case for the majority of us). If you’re compromising relationships and the enjoyment of time spent with family and friends for ‘clean eating’, I would contend that your priorities need to be reevaluated. Even for the select few individuals who are professional athletes, the ‘sacrifice to win” mentality is completely masochistic if it doesn’t offer some tangible performance advantage. It seems that many people in the fitness industry like to wear masochism as a badge of honor; as if not eating food that tastes good is some type of moral imperative. The adherence to ‘clean eating’ can almost be religious in nature, even imparting a sense of piety to the clean eater. I’m sorry, but you’re not better than someone else because of what you eat; you aren’t more committed and flexible dieters aren’t more ‘lazy’ just because they enjoy food that doesn’t taste like cardboard. The sense of piety that often accompanies ‘clean eating’ reinforces the superiority complex that begets what is essentially an eating disorder, and we certainly see a good number of cases of orthorexia when clean eating becomes compulsive (5,6). Furthermore, strict clean eating just isn’t sustainable for most people psychologically; this is why you see so many people lose weight then go ahead and put it all back on, plus a few more pounds (7).

Here is the crux of flexible dieting; no food (with the possible exception of those containing hydrogenated oils and certain acutely harmful compounds) can be considered healthy or unhealthy in isolation, outside of the context of one’s overall dietary intake. For food to be classified as healthy or unhealthy based on its macronutrient profile is absurd, to be frank. Flexible dieting doesn’t just include counting macronutrients; but the different forms of a particular macronutrient, as well as micronutrients and phytonutrients. What usually trips people up regarding flexible dieting is the energy equation. Losing body tissue mass or gaining body tissue mass is dictated by one’s energy balance; calories in vs. calories out, and body recomposition (e.g. fat loss and/or muscle gain) is dictated by macronutrient partitioning (and of course one’s physical training). Clean eating advocates will say “well 4,000 calories of pizza isn’t the same as 4,000 calories of chicken and broccoli, so a calorie isn’t a calorie”; this is simply because they don’t understand the ‘calories out’ side of the energy balance equation.

The Energy Balance Equation

Your total calorie expenditure is determined by the following five components: Basal metabolism; which is the amount of energy required to sustain basic bodily functions if one were completely immobile (this varies based on genetics, body composition and body size), the thermic effect of food; which is the amount of energy required to digest, absorb and dispose of food, the thermic effect of activity; which is the amount of energy used during exercise, non-exercise activity thermogenesis; which is the amount of energy used going about every day activities, as well as idiosyncratic movements (e.g. knee bouncing while sitting down), and the adaptive component; which is the change in one’s resting energy expenditure based on one’s activities and dietary intake (2). The adaptive component is by far the most complex or the factors and is the hardest to measure, and it really deserves its own article; many of which have already been written, particularly in regard to metabolic damage.

It is the thermic effect of food which accounts for the change in the energy balance equation between the 4,000 calories of chicken and broccoli and the 4,000 calories of pizza. Quite simply, the 4,000 calories of chicken and broccoli are less energy efficient. This is perhaps where I do need to give a tip of the hat to clean eating, as generally they consist of low to moderate amounts of fat, are very high in protein, as well as high in fiber. High protein diets quite simply are less energy efficient by default because protein causes the highest thermic effect (1, 2). For example, the conversion of alanine to glucose during the process of gluconeogenesis (the synthesis of glucose from non-carbohydrate macronutrients, namely amino acids) requires 6 ATP molecules and the conversion of pyruvate to glucose requires 6 ATP molecules (9, 10). Additionally, 4 molecules of ATP are required to dispose of excess nitrogen, the byproduct of protein metabolism, as urea (9). The thermic effect of nutrients is approximately 2-3% for fats, 6-8% for carbohydrates, and 25-30% for protein (11). Fiber in particular is the wild card, as it causes a high thermic effect without providing 4 calories of energy per gram like regular carbohydrates. Insoluble fiber in particular has zero caloric yield to humans, as it cannot be metabolized. Fiber also happens to be very satiating as it slows gastric emptying, reducing the food cravings which often compel overeating (3,4,8).

Insulin and the Glycemic Index

One of the standards that is most often used be clean eaters to determine whether a food is ‘clean’ or not, is the glycemic index. The glycemic index is a measure of how quickly blood sugar levels rise after eating a particular type of food. Using glucose as the benchmark (at a GI value of 100), the glycemic index approximates how much a food raises a person’s blood glucose levels following consumption of the food.

The Glycemic Index is based on fasted insulin response from foods consumed in isolation, which for any practical dietary implementation is wholly meaningless because nobody eats one single food for an actual meal unless it’s a small snack; throw in some fats, protein or fiber, all of which slow gastric emptying, and you can throw the glycemic index out the window.

To be quite honest, at this point, I think it would be better if most gym rats, strength athletes, and even bodybuilders (minus the ones that actually inject insulin) knew nothing at all about insulin. It seems that nearly all the benefits of dietary thermogenesis and the effects of dietary fiber on metabolism in particular, are usually misattributed to insulin secretion (or the lack thereof). 100 grams of sucrose (table sugar) are going to cause the same amount of insulin secretion as 100 grams of starch from potatoes; however the body requires more energy to hydrolyze a chain of polysaccharides than it does to digest a simple sugar. Fiber in particular, accounts for most of the metabolic advantages of whole food carb sources over processed sources, as it has minimal caloric yield and causes a high degree of thermogenesis (13). It is true that insulin stimulates postprandial fat storage (the fat storage that occurs after you’ve eaten a meal). However, this does not dictate net body fat gain, because once insulin returns to baseline, and blood glucose levels drop, the body secretes glucagon and you go right back to breaking down body fat. In other words, acute fat storage isn’t what matters – net body fat balance (fat storage minus fat breakdown) over the long term is what dictates fat gain or fat loss (14).

Now, this might lead you to believe that reducing overall insulin secretion, as opposed to acute insulin secretion, would lead to greater fat loss. If macronutrient partitioning were to be kept the same, this may be true, but this isn’t due to anything special regarding insulin, but the fact that, by default, this would require a reduction in overall macronutrient (and thereby caloric) intake. Insulin is secreted in response to elevated blood glucose levels – whether this elevation happens rapidly (in the case of simple sugars on an empty stomach) or over an extended period of time is irrelevant to total insulin secretion (I won’t go into the issue of insulin resistance here, as that is another topic). This also isn’t true because insulin isn’t required for fat storage. Even in the complete absence of insulin, which for all practical purposes isn’t tangible as protein is quite insulinogenic, fat storage can occur via acylation stimulating protein (15).

In the end, moderation and flexibility are the cornerstones to healthy, sustainable dieting. I think it’s time that we stop selectively demonizing particular foods, and realize that, in the correct quantities, all foods from ice cream and pizza to egg whites and broccoli can be consumed in calculated portions to achieve optimal health and performance. With flexible dieting, we can have our cake and eat it too.

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4. Weickert MO, Mohlig M, Koebnick C, Holst JJ, Namsolleck P, Ristow M, Osterhoff M, Rochlitz H, Rudovich N, et al. Impact of cereal fibre on glucose-regulating factors. Diabetologia. 2005;48:2343–53.

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7. Meule A, Westenhofer J, Kubler A. Food cravings mediate the relationship between rigid, but not flexible control of eating behavior and dieting success. Appetite. 2011;57(3):582–584. doi:10.1016/j.appet.2011.07.013.

8) Wardlaw GM, Kessel M. Energy Production and Energy Balance. In: Perspective in Nutrition 2nd Ed. New York, NY: McGraw-Hill Higher Education; 2002. p. 535-537.

9) Hue L. Regulation of gluconeogenesis in liver: In: Jefferson L, Cherington A, eds. Handbook of physiology: the endocrine system. Vol 2. Oxford, United Kingdom: Oxford University Press, 2001:649-57.

10) Bier DM. The energy cost of protein metabolism: lean and mean on Uncle Sam’s team. In: The role of protein and amino acids in sustaining and enhancing performance. Washington, DC: National Academies Press, 1999:109-19.

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14) Díaz EO, Galgani JE, Aguirre CA. Glycaemic index effects on fuel partitioning in humans. Obes Rev. 2006 May;7(2):219-26.

15) Jumana S, Summers L, Cianflone K, Fielding B, Sniderman A, Frayn K. Coordinated release of acylation stimulating protein (ASP) and triacylglycerol clearance by human adipose tissue in vivo in the postprandial period. April 1998. The Journal of Lipid Research, 39, 884-891.

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