Are carbohydrates really the problem?
In an age where all nutritional information is just one click away, we find people who tell you how fattening food is while they drink their coffee with a chunk of butter. It is not unusual to hear claims like: “Carbs are the problem”, “Insulin is responsible for your being fat” or “Calories don´t matter if you do a ketogenic diet”.Before presenting why all these claims are incorrect, I would like to emphasize that I have nothing against low carb diets and that even I use them as a tool for many of my athletes when I am after improving body composition, however, the reason is not due to a ‘metabolic advantage’ with other diets, but much more simple reasons.
Creating a caloric deficit
Many people who argue agains the CICO theory fall into the trap of believing that we are dealing with a static system, when we are actually talking about a dynamic in which our body varies its response according to the caloric intake. In other words, the amount of calories we ingest affect the amount of calories we expend. It has been shown in several studies (1-6) that when we increase the caloric intake (and thus increasing body weight) it can lead to increases in the total daily energy expenditure (TDEE), while when we cut down our caloric intake, we are reducing the amount of calories we burn in a day. In this way, we will see that de actual long term weight loss will be inferior than expected (7) regardless of whether we are on a low or high carb diet. Even so, we have to take into account that the person’s behavior will influence more their weight loss results than the metabolic adaptations.
When we consider the dieter’s behavior, we can observe that most of them underestimate their intake or overestimate their expenditure (8-13), even though they know that the researchers themselves are watching them (14). On the other hand, we find that when the person know the amount of calories he or she has expended, they feel freer to ingest palatable foods. (15). Considering that nowadays, most people use wearable devices that overestimate expenditure during training (16), the difference between reported calories vs actual caloric intake is even larger. This is one of the reasons why we find inconsistencies when we compare low carb vs low fat diets in conditions where subjects are free to do what they want.
Another limitation is that many of the studies used at favoring low carb diets have a superior protein intake, consequently we wouldn’t be speaking about high carb diets vs high fat diets, but about high protein diets vs low protein diets. This is a major factor since when we increase protein we lose less fat free tissue, our appetite is reduced and even (in a modest way) we increase TDEE (17-23).
So, what happens when we control the calorie and protein amount in both diets?
When we review the studies in which both parameters are controlled for, we see there are no significant differences. Golay et al (24, 25) reported that when protein and caloric intake were identical during a severe caloric deficit, there was no difference in fat loss between having 15% or 45% of the total energy intake in the form of carbohydrates. Hall et al (26) reached the same conclusion in their study, where they reported no difference in fat loss between a ketogenic diet and a moderate carbohydrate diet when calories and proteins where matched. Further, a meta-analysis performed by Johnston et al (27) concluded that the difference between both diets had a minor difference of only 0.2kg (0.44lb) for a whole year.
Adapted from Hall et al (2016).
Adapted from Johnson et al (2014).
And here is where the real problem is: Every diet fails in the long term if there is no adherence.
Regardless of the diet’s carbohydrate intake, we see that in the period from 6 months to a year is when most people regain part of the lost weight (metabolic adaptations, lack of adherence to the diet, more hunger…) Thus, blaming carbs as the only cause for obesity makes no sense at all.
On the other hand, is there evidence that you can loss a lot of weight while consuming a very high carbohydrate diet .The answer is yes!
For that we have to call upon the 40’s, when Walter Kempner’s diet known as ‘the rice diet’ made the spotlight. This diet is based exclusively on rice, vegetables and fruit, which made the carbohydrate intake over 90%. Leaving aside the fact that we´re not talking about an ‘optimal’ diet due to the lack of protein and fat intake, it really helps us understand how carb intakes over 500g, could make someone lose more than 45kg (99lb) of body weight (reaching over 100kg (220lb) in some guy) if they are in a caloric deficit (28).
Subjects from Walter Kempner’s study.
Currently, we have populations like the Kitavas or the Okinawas where the carbohydrate intake is reported to be over 70 and 90% of their total caloric intake respectively and somehow, they don’t exhibit obesity nor 21st century diseases because their caloric intake isn’t high (29-35). It would be expected that within a framework where the caloric intake (mainly carbs) is very high, our body would shift from the usage of fatty acids to carbs as a main source of energy. This fact will make no time for the ingested fat to oxidize completely and therefore be stored in the form of triglycerides and fat tissue. Thus, we can say that whenever we speak about caloric surplus, the dietary fat storage will be more effective than the carb surplus and therefore, lipogenesis would not occur easily again, at least in humans.
At the end of the day, it is energy balance that determines fat loss to a greater or lesser extent and not if you are following a high or a low carbohydrate diet. Adherence to the diet is an important cornerstone if we want to achieve long term fat loss and to accomplish this, we have to educate people making them see that whether they follow a high carbohydrate diet or a high fat diet, you can achieve your goals as long as you are in a caloric deficit and you find a diet that is sustainable for you in the long run.
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