J Beaty: What are your thoughts on the reemergence of the macronutrient food combining theory where carbs shouldn't be mixed with protein/fat meals and fat shouldn't be mixed with protein/carb meals?
L Norton: This is a rather simplistic way of looking at nutrition and focuses mainly on insulin rather than looking at the whole picture. While it probably isn't
a good idea to have a really high carb meal with a really high fat meal, there's nothing wrong with having moderate amounts of both.
W Brink: Like many theories, it comes around every few years or decades and gets people all worked up over their food. Problem is, it's no more true today than it was when the book “Fit for Life” by Harvey and Marilyn Diamond came out. The theory had no scientific support then and it has none now. Humans have been combining fats, carbs, and proteins quite successfully for eons, and as omnivores, are perfectly capable of digesting mixed meals.
J Hale: You are probably referring to the theory that assumes insulin and blood levels of fat should never be raised at the same time. This theory assumes that insulin is the key contributor to obesity. There are a few things wrong with this line of thought. One of the key problems is not recognizing something called Acylation Stimulating Protein. Acylation stimulating protein (ASP) is a hormone produced by adipocytes and is of importance for the storage of energy as fat. The consumption of dietary fat alone can increase fat storage. Dietary fat affects fat cell metabolism with NO INCREASE in insulin. Some studies have indicated dietary fat loading found a decrease in HSL (hormone sensitive lipase) and an activation of fat storage despite no increase in insulin. The key reason was activation of acylation stimulating protein (ASP) which is activated by the presence of chylomicrons (basically packaged triglycerides that are found in the bloodstream after the meal). ASP increases glucose uptake into the fat cell, increases insulin release from the pancreas and has been described as 'the most potent stimulator of triglyceride storage' in the fat cells by numerous scientists. Another problem with this line of thought is some proteins cause substantial elevations in insulin. Minimal levels of insulin affect fat cell metabolism. Basal levels can decrease lipolysis by 50%. Another consideration is most bodybuilders are eating every 2-3 hrs so nutrients are still absorbing from previous meals; therefore previous meals interact with the blood levels of nutrients of the present meal.
A study conducted by Golay and colleagues compared a diet with equal macronutrient content and substrate percentages; that differed only in how the substrates were consumed (mixed diet vs. food combining). The results were no difference in weight loss. Here are the exact results reported by the researchers:
“Results: There was no significant difference in the amount of weight loss in response to dissociated (6.2 +/- 0.6 kg) or balanced (7.5 +/- 0.4 kg) diets. Furthermore, significant decreases in total body fat and waist-to-hip circumference ratio were seen in both groups, and the magnitude of the changes did not vary as a function of the diet composition. Fasting plasma glucose, insulin, total cholesterol and triacylglycerol concentrations decreased significantly and similarly in patients receiving both diets. Both systolic and diastolic blood pressure values decreased significantly in patients eating balanced diets. The results of this study show that both diets achieved similar weight loss. Total fat weight loss was higher in balanced diets, although differences did not reach statistical significance. Total lean body mass was identically spared in both groups. CONCLUSION: In summary, at identical energy intake and similar substrate composition, the dissociated (or 'food combining') diet did not bring any additional loss in weight and body fat”. Actually looks like a slight increase in fat loss with mixed diet (balanced diet).
We have tons of anecdotal evidence that denies the need for food combining. We have evolved on a mixed diet. With all of that said, food combining may be beneficial regarding calorie control. Once you eliminate an entire macronutrient from a meal, this can go a long way in decreasing total caloric intake. If this is what you need to do to control energy intake, feel free to do so.
A Aragon: I think that the “P+C & P+F = okay but avoid C+F” principle is idiotic when applied across the board without any contingencies or attention to individual situations. For example, is someone is low-carbing for whatever reason you choose (pathological carbophobia included), they might be done with their carb intake by early afternoon, and their meal construction for the rest of the day is gonna be primarily P+F by sheer default. In the latter scenario, I can see the principle being legit.
However, when issued blanketly, it’s usually based upon the wacky idea that you don’t want fat floating around systemically when your insulin levels are high, because this will magically shift your net adipose balance in the positive. That’s false for a number of reasons. First of all, the insulin response generated by CHO + fat generally depends upon the degree of the fat’s saturation. Unsaturated fats tend to either lower insulin response of the co-ingested carbs, or not affect insulin response at all. Co-ingested sat fat, on the other hand, tends to raise insulin response, and can do so in a synergistic fashion. But then the question becomes, so what? Others have mentioned the more direct role ASP has in TG synthesis, and indeed, insulin is more of a multi-tasking anabolic/anticatabolic agent in comparison to ASP, which seems to exist solely to pump up the adipocytes. And of course the kicker is that ASP can do its TG-synthesizing magic in the sheer absence of insulin.
And then there’s energy balance… In a negative energy balance, insulinogenesis is wonderful thing, as long as the training stimulus & nutrition is there to work in concert with it to preserve LBM. In the condition of a positive energy balance, trainees in general are gonna have a lot more carbs to throw around, so this makes the whole separation thing even more dicey. Which meals should be carb-free or fat-free in order to pull of this magic separation tactic, and why? The logical answers to this question simply don’t exist. If you were to actually adhere to the mechanics of separation, you’d actually be hard-pressed to maintain a stable insulin profile – which is ironic, since the control of insulin is what “separatists” are aiming for. Regardless of all the previous points, the fundamental short sight is that digestion/absorption of meals overlap each other when meal frequency is as high as it should be. Therefore, attempting strict separation of the macros = kidding yourself. Not to mention, most foods in nature are a combo of all the macros to begin with.
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