The most important prerequisite for one to gain body fat is assuming a caloric surplus. Simply put, you will not gain fat if you are not eating above your required caloric intake. You must eat more calories than you burn in order to gain weight and store new body fat. Not surprisingly, the same concept holds true for protein synthesis and muscular hypertophy (you cannot gain weight in the form of new lean mass without assuming a caloric surplus of some level). This is the reason for the term "calorie is king". Now, I'm not saying that the overall composition of ones diet (i.e. what makes up those calories being consumed) does not sway the type of weight gain one experiences (i.e. muscular gain versus fat gain) and I'm not saying calories are EVERYTHING (i.e. ignoring the hormonal aspects and ignoring how the different macronutrients influence different hormonal responses). The macronutrient composition of ones diet is certainly important in determining the aesthetics of ones physique. Yet, one can not ignore the basic truth of calories at a prime level. That is: without an excess of calories present above ones maintenance needs, the above truths of hormonal influence of the different macros is practically moot.
Therefore simple truth: You must eat more calories than you burn in order to gain weight and store new body fat.
I'd be willing to bet that many of you have heard someone tell you along the way that carbohydrates make you fat. Or, you have heard a comment that resembles the above in some way. Perhaps, you believe that carbohydrates simply turn to fat in your body and get stored as such. Things are not quite that simple. Therefore, let's clear up this particular misconception. It is true that carbohydrates can contribute to fat gain. However, this is typically an indirect effect. First, in accordance to the beginning prerequisite, let's assume that a caloric surplus is being consumed. Carbohydrate consumption creates a condition in which the body will stop burning fatty acids for fuel. If one consumes carbohydrates, the body will preferentially utilize those carbohydrates as energy substrate over the usage of fatty acids as energy substrate. In a caloric deficit, this would not matter at the end of the day because overall calories consumed are less than overall calories burned. In a caloric surplus, it would matter. Because your body gives carbohydrates preferential treatment as fuel, the dietary fat intake for that day will be stored. Carbohydrate intake is contributing to fat gain in an indirect way. The carbohydrates themselves are not being converted to body fat, rather they are being utilized as fuel, preventing the usage of fatty acids for fuel and the dietary fat that you have consumed for that day will simply be stored as body fat.
|Process of DNL in the liver.|
Can carbohydrates DIRECTLY contribute to body fat gain via being converted to fatty acids and stored as such? In short, yes. Carbohydrate consumption can theoretically lead to fat gain other than in the indirect way described in the previous paragraph. The process by which carbohydrates are converted into fatty acids is known as de novo lipogensis. In order for DNL, one must assume a caloric surplus. One must also assume that glycogen stores are completely maxed out in the body. This is something that would be unlikely to occur in a normal humans diet. You would have to consume VERY large quantities of carbohydrates for multiple consecutive days in order to truly realize 100% glycogen capacity in the body. Only at this point would your body begin to convert carbohydrates into fatty acids directly and store them as such. Common sense will tell you that this is certainly a more difficult process for the body than the indirect process described above. We now need multiple prerequisites to be met and the body needs to complete a conversion process. Simply put, your body is not going to go through all of that unless it really HAS to. It wouldn't really HAVE to unless you were eating over your caloric maintenance level and consuming A LOT of carbohydrates (enough so to top off glycogen stores 100% over a period of days).
Therefore simple truth: carbohydrates themselves do not typically lead to fat gain in a direct manner but, rather in an indirect manner.
Protein consumption can lead to fat gain in the same manner described above. That is, when you eat protein your body will prefer to utilize such and therefore stop utilizing fatty acids as energy substrate. Is there a trend here? Apparently so. The process of DNL for excess carbohydrate consumption is typically unlikely under normal circumstances. The same is true for excess protein consumption; even more so than that of excess carbohydrate consumption. The metabolic pathways for excess calories via protein intake to be converted into body fat is complex, lengthy, and unlikely to actually transpire under any notion of normal conditions. This is in fact much more unlikely than even the direct conversion of carbohydrates into fatty acid and subsequent storage as such.
Therefore simple truth: excess calories via protein consumption almost never leads DIRECTLY to fat gain but, can lead to fat gain via an indirect manner (similar to the indirect manner in which carbohydrates lead to fat gain).
The people who really grasp the concepts above will usually go on to ponder such and maybe ask the question: Well, can I just pig out on carbohydrates and protein in hedonistic excess and avoid fat gain by keeping dietary fat intake at practically zero? Unfortunately, no...not really. It is true that if you were to eat a caloric surplus and the majority of such calories were by way of protein and carbohydrates and low dietary fat intake, then actual body fat storage would likely be relatively low. One would still experience a temporary gain in body weight, but this would be due mainly to water weight gain and glycogen storage. However, you cannot simply keep dietary fat intake at practical zero and consume pure carb/protein meals in ridiculous abundance and expect to gain no body fat. Apparently, tricking the human body is not that easy. Here is why: when one reduces dietary fat intake to extremely low levels as described above, then the previously explained process of de novo lipogenesis is ramped up greatly. That is, the process by which carbohydrates are converted to fatty acids and directly stored as such becomes heightened greatly when one drops dietary fat intake to an extreme low. Therefore, if one is going to assume a large caloric surplus and wants to avoid major body fat gain, then it is best to consume mainly carbohydrates and protein meals and keep dietary fat intake relatively low (but, not extremely low). The dietary fat intake for that day will be stored as such however, it won't be too significant. The other weight gain experienced will be via glycogen stores and water weight, of which are both temporary.
Now, when someone tells you that carbs make you fat, then you can tell them that they are correct, but not in the way that they probably believe to be so.