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Intermittent fasting (IF) and If It Fits Your Macros (IIFYM) are some other hot “diets” right now. You will see people on YouTube eating McDonald’s and claiming they looked jacked and shredded because of IF or IIFYM and can still eat crap food. This just simply isn’t 100% accurate. These people most likely are on some “enhancer” like steroids or SARMs so their metabolism and muscle building capacity are elevated beyond us “normal” people. I will explain why these diets work and why they don’t work in this post.
Intermittent Fasting (IF) is basically where you go through an extended period of fasting (not eating or consuming calories – drinks have calories too). This leaves you with an “eating window” where you can consume calories. Some IF programs have you fast for a full day or more but most IF programs have you fast for about 16 hours each day (and everything in between). There are reportedly numerous benefits to having your body in a fasted state. However, a lot of these claims are not scientifically proven or have such a minuscule impact on your body that there is no “secret metabolic advantage” to using this diet. Just like the Ketogenic or Atkins diet (see my past post) this simply gets people to eat less and thus they are in a hypocaloric state. You will lose weight on this diet as long as your total daily calories are less than what you are consuming still. For example, if you fast for a day and then eat “normally” for a day your average daily caloric intake is going to be half of your normal intake, thus hypocaloric.
IF is very helpful if you tend to “stall out” or “plateau” on your normal diet or on a ketogenic diet. IT is especially helpful in a ketogenic diet because your body turns to ketogenesis (producing ketones, which is the major plus of the ketogenic diet) in a starvation state as well as a low carb state. However, you have to remember that ketogenesis doesn’t equal weight loss. Ketones are simply the energy source your body is running on in a starvation or low glucose (carbohydrate) state. Generally speaking, however, more energy = more motivation = longer or harder work in your workouts. So if you love the ketogenic diet and love the way your brain operates on ketones (most people do) then try to throw in IF (especially if you have reached a weight loss plateau).
Can you build muscle on IF? No surprise here that it is not optimal, just like the ketogenic diet. Once again, you are in a hypocaloric state and thus will likely not build much muscle. However, if you are shoveling a large amount of calories in your mouth during your eating window and end up hypercaloric (in a caloric surplus) then you can definitely build muscle (and fat) but you are not optimizing this process by not feeding your muscles and spiking your NO frequently due to fasting. Plus, muscle glycogen is pretty empty in a fasted state and that equates to less strength in the gym, which makes it harder to progressively overload your muscles. IF has been hailed as “muscle sparing” similar to the ketogenic diet, but this is a relative term. It is RELATIVELY muscle sparing compared to your basic hypocaloric diet (or most definitely compared to an extreme hypocaloric diet). The ketones produced during fasting or starvation tend to help spare muscle wasting to a certain extent, but they don’t stave off muscle wasting 100% and won’t help you build lean muscle. I do believe it is still possible to build muscle in a very slight caloric deficit (assuming you are eating large amounts of protein as well) but it is not optimal.
If It Fits Your Macros (IIFYM) is another popular diet lately, and I don’t really understand why. This diet basically has you tracking your macronutrients (macros) and you can eat whatever you want as long as you meet, and don’t go over your macro limits (protein, fats and carbohydrates). This diet operates under the presumption that it is “easier” than traditional dieting because it suggests that all macronutrients are created equal. For instance, they believe a carb is a carb (1 g worth of sugar is the same as 1 g of whole wheat bread because they are both 1 g of carbs). I personally don’t buy into this because the body handles simple sugars differently than complex carbohydrates regarding insulin spikes and many other biochemical pathways. We also know for a fact that not all fats are created equal. Saturated fats are not as healthy as unsaturated fats and both are a better option than trans fats. Hell, not all protein is created equal either! We have very fast digesting whey protein and slow digesting casein protein and many in between. We have whole proteins or hydrolyzed protein fragments. I don’t buy into a diet that preaches a fast food burger and fries are “healthy” just because it fits your macros. I don’t think I need to go off on a rant about all the other processed food and fillers that are in a lot of fast food. Not all macros are created equal and that shuts down the very premise of this diet.
Besides the reasons mentioned above, you’re also only one step away from tracking your calories. Why would you go through all the trouble of tracking the amount of protein, carbs and fats in a meal and ignore calories? You’re literally a millisecond away (unless you are a really slow reader) from doing a traditional diet and you likely went through more trouble to ignore the calories since they are labeled first on nutrition labels. So why does this diet work for some people? Because you are basically doing a traditional diet (tracking calories and macros like I explain in the Basics of Nutrition post). Each macronutrient has a defined caloric value to it. Protein and carbohydrates each have 4 calories per gram and fat has 9 calories per gram. So you are basically still eating a hypocaloric diet by only tracking your macros (assuming you are doing it right) but you simply aren’t paying attention to the calories, even though the math still exists in the background and that caloric math is the real reason you are losing weight on this diet. So why not just track calories and macros and don’t eat a lot of crap fast food? Because people make more money off of selling you diets that you CAN eat that crap and try to claim it is “easier” than traditional dieting. Can you lose weight eating junk food as long as it fits in your macro or calorie limits? Possibly, but the number on the scale and your body fat percentage are not the only measure of health here. Inflammatory markers, blood glucose, cholesterol, etc. still matter. You can still lose weight with occasionally eating fast food (I love me some cheat meals), but it is not OPTIMAL and you will not lose weight if your calories and macros are made up from a dollar menu.
Once again it comes down to one question: is this diet SUSTAINABLE for you? If the answer is yes, give it a try. If the answer is no, then why not just take the the extra two seconds and track your calories? Why starve yourself and skip breakfast if you’re going to be miserable and lose muscle mass (IF)? there are a number of people that love these diets and do well on them and sustain that success. But these diets are not for everyone and now you know WHY they work (when they actually work). If you understand the driving principles of how these diets work then you can apply them to ANY meal on ANY diet that you want. I’ll say it again, it all comes down to creating healthy, sustainable eating practices. If you eat less calories than you burn, you will lose fat. The smaller the caloric deficit the better chance you have to keep or even possibly gain muscle while still losing fat. So take the time, put in the work and find your sweet spot for your maintenance calories and tinker with it after a couple of weeks to make sure it’s working for you. There are no quick fixes or “easy” diets out there. There are no hacks to a proper fitness lifestyle. You have to put in the work and pay attention to what goes into your mouth.
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