The most important thing about changing your body is total calories in vs total calories out, there is no way around that. This is the most important thing, not the ONLY thing. Secondly, the macronutrient breakdown of those calories will determine what kind of weight is coming on or off of your body. Finally, every other factor such as meal timing and even calories burned from working out come into play and are much much less important. If you eat junk, you will be a hungry person on this kind of nutrition strategy. You will also most likely gain fat more quickly.
I have done (and continue to do) a lot of experimentation on myself with respect to nutrition, figuring out along the way what is effective and what is not. As a partner at Cambridge Strength and Conditioning,  I also advise our members on nutrition. This work has lead me to develop my personal philosophy about nutrition: my three pillars of nutrition. These pillars are in order of priority. Pillar 1 is your top priority, pillar 3 is your least important priority. If you haven’t figured out pillar 1, there is no use going on to pillar 2.
Pillar 1: Total Calories
The first step in any program is to figure out what your total daily caloric intake should be for your goals. Think of this as an average over the week. For example you can eat more on gym days and less on rest days, but just make sure you’re hitting the total number of weekly calories that you need to meet your goals. Why is this so important? This is the single greatest factor that determines what happens on the scale. I cannot emphasize this enough. You are consuming thousands of calories per day, and also expending thousands of calories per day. I like to split calorie expenditure into three categories. Most of the calories are burned from simply being alive. This first category is called your basal metabolic rate (BMR), the amount of calories that you burn if you don’t move at all. The second category is calories that are burned simply by performing your daily activities. Even if you are sedentary, this second category does add up to quite a bit of additional caloric burn. Finally, your time in the gym is the third category of your caloric expenditure. There are certain types of athletes (for example, endurance athletes) that can burn an enormous amount of calories in their workouts because they are so long, but generally an hour of cardio might get you 500kcal if you’re lucky. Most lifting workouts are even less caloric expenditure than that. The key point to remember is that this third category, while often feeling like the most “productive” towards your goals, actually only contributes a small fraction of the total calories you expend in a day.
How to set your caloric goal
The good news about all of this is that you don’t have to think too hard about how to set a caloric goal. The first step is measurement. This is priority one. If you do not know how many calories you’re putting in your mouth you cannot accurately manage your weight. I highly encourage you to commit to using an app to count calories for one week. The most difficult part is getting set up, but once you’re through the first week things become much easier. Apps make this so much easier than it used to be, so please take advantage. Weigh yourself daily on the same scale, preferably in the morning before your first meal and after the morning poo/pee. This is the most stable time to measure your weight. I personally use a Fitbit Aria to measure my weight with IFTTT to sync to my google drive in a spreadsheet. This makes data collection very easy. Take a look at a 7-day average of your weight and the trend of it, is that moving up? Is it moving down? The likely scenario if you’re not making a conscious effort to change your body is that it is very stable. If your weight is stable then you are eating at total daily expected expenditure (TDEE). That essentially is the definition of TDEE. If you are losing weight it is because your TDEE is greater than your caloric intake from food. If you are gaining weight it is because your TDEE is less than your caloric intake from food. A general rule of thumb is that 1lb gained or lost per week is worth roughly 300-500 calories. Thus if your weight is stable now, adding 300-500 kcal per day should result in gaining about 1lb per week. Of course, you can be more aggressive than that if you choose.
Something else to keep in mind when trying to gain weight is that as you gain weight your TDEE will increase (mainly because your BMR is increasing). This means that you need to add even more calories to maintain a surplus. If you don’t continue to increase your caloric intake, the first week will see a solid response with subsequent weeks showing less and less response until you reach homeostasis (no weight gain) again. Every 2-3 weeks the calories should be adjusted upward to maintain weight gain as long as you want to keep gaining weight. Something that you will eventually have to watch out for is losing insulin sensitivity, but you can bulk up for quite some time before having to address this. This issue is effectively addressed by cutting weight, for example with a ketogenic diet.
Pillar 2: Macronutrients
In order of importance, macronutrient intake is second only to caloric intake. The three macronutrients are carbohydrates, protein and fat. Carbohydrates and protein have roughly 4 kcal per gram, while fat has more than double that at 9 kcal per gram. The first priority is figuring out tagret amounts for each one of these macronutrients, then hitting those targets. Let’s dive in to each of these individually.
Protein is by far the most important macronutrient for putting on lean mass. Before we get too technical about this thing let’s just think about it from a really simplistic viewpoint. Animals have muscles. Humans are animals with muscles too. If we want more muscles, we should eat the muscles of other animals, they will stick to us. This is really not too far from the truth with a whole lot more science involved it’s basically a good mental model. The molecules that make up the muscles of animals are protein.
The number one dietary issue that I have seen in my trainees is that they aren’t consuming nearly enough protein. There is very little downside to consuming “too much” protein. There is technically a path for protein to be stored as fat but this is a very unlikely event. Protein is the nutrient required for your body to rebuild muscle. When you train, micro-tears are created in the muscle fibers. These are repaired in the presence of free proteins. It is critical to have enough protein available to your body to recover from training, this is how we grow muscle.
The question then becomes, what is the appropriate amount of protein? This is a highly contentious issue that has been beat to death but in my personal experience I always find the academic studies do not agree with strong guys in the gym. The biggest issue with most of these studies is that they deal with novices. Almost any novice is going to be able to put on muscle if they go from being couch-bund to working out and eating additional protein. Their progress is so rapid that additional protein is not helpful because they’re already building as fast as possible. It is when the novice hits the plateau that they require additional protein. The appropriate amount of protein is a wide range from 1g/lb of body weight to 2g/lb of body weight. This is what is effective in my personal experience with my own body, when working with trainees and when talking to very experienced lifters whose opinion I respect very highly.
This is going to sound like a lot of protein to many people reading this and in all likelihood it is significantly more than you’re eating today. Let me just say that the absolute worst possible case of trying to consume this amount of protein is that it ends up in the crapper, literally. It is very unlikely to make you fat unlike many recommendations such as GOMAD and others. How the heck can one person eat so much protein? Put it in your face and stop making excuses.
The easiest way to accomplish this is with protein shakes. The first problem with common usage of protein supplementation is that the scoop is so small and the recommended serving size is so small relatively speaking. If you need to eat 200g of protein per day MINIMUM and the main tool that you have to help you do that is only providing 30 grams per day that is going to be a problem. The second issue that most people have with protein shakes is that if they try to up the number of scoops they get serious poo issues. That is because there is no dietary fiber going in with all this protein so it goes out just the same way it came in. Adding dietary fiber to protein powder is an excellent way to make sure that you don’t crap your pants every time you sneeze. Some people have a lactose intolerance which makes this difficult, that can be addressed by eggs mainly but it does make the whole gain lean mass endeavour much more expensive. I don’t encourage drinking raw egg whites though, I have never tried it but there are obvious risks involved.
Carbohydrates are chains of one or more monosaccharides such as glucose. The longer those chains are the more effort in digestion it takes to release the components. This helps you feel full longer and spreads out the amount of time for the sugar to enter the bloodstream. These are the so-called “complex carbohydrates” and “slow carbohydrates”. See more about this very interesting topic here . Fiber is actually counted as a carbohydrate on food labels even though the bonds that hold the monosaccharides together cannot be broken down by the human digestive system. Insulin is your friend because it helps our body grow but if you release too much of it too quickly it will make you fat especially in an abundant fat environment.
Carbs are very important for growth because they have a very strong insulin response. Insulin is a very anabolic (growth) hormone, it naturally tells your body to GROW NOW. The easiest way to release insulin is to eat glucose. This will spike your blood sugar and cause your body to release insulin. The main reason this is bad is that this will cause you to store this glucose mostly as fat unless you are in a very low blood sugar state already.
Our goal is to control the blood sugar level so as not to release too much insulin that would cause you to store the blood sugar as fat. That is why fat and simple sugar taste so good together. When you get that flavor combination, your lizard brain says, wow this is an incredible food, you should really try to find some more of this before we starve this winter. Lucky for us, we don’t need to worry about getting through the winter and not running out of food anymore, we have that one figured out.
That leads to the question of fat. When do high fat diets make sense? When do they not make sense? The only way high fat diets make sense is if you are in ketosis. This means that your body is using fat as fuel because you are not providing it with enough carbohydrates. There are a TON of resources out there about keto diets so I am not going to get into that right now. The only thing that I want to add to what is out there is that there is no appropriate middle ground when it comes to fat. You should be either eating high carb/low fat or low carb/high fat. There is no middle ground that makes sense where you stay lean. When I say low fat and low carb, those are set in absolute terms. Low carb means ketosis, this is different for different people but generally speaking less than 10 grams of carbs for induction to up to 50 grams once you’re in ketosis. If you aren’t in ketosis, you cannot say you are eating “low carb”. The good news is that there are test strips for determining if you’re in ketosis available in the diabetes section the drug store. Low fat means less than 50 grams of fat per day. This may be slightly lower if you’re a short person or female. Fats should be polyunsaturated fatty acids (PUFAs) especially omega-3 and omega-6 fats. Some cholesterol in your diet is not bad as it is required for production of testosterone and other hormones but it can be synthesized by the body from available fats without being eaten directly unlike essential amino acids.
Pillar 3: Everything Else
I have saved an entire pillar for literally everything else diet related. Broadly the rest of the issues fall into two categories. First, what kinds of foods you’re eating. Second, when you eat those foods.
What kind of food you’re eating mainly matters because that has a lot to do with what kind of weight you will be adding or removing. That is predicated on the fact that you’re eating your target macros to begin with. If you’re eating 95% of your kcal in carbs, that needs to be fixed first. Carbs should be slow carbs. These are things that may even have fiber in them which is the “slowest”. You want nice long digestible chains.
Fats should be polyunsaturated omega-3 and omega-6 fats as well as medium chain fats (MCTs). Flaxseed meal and cod liver oil are excellent sources of omega 3s. Omega 6 fats are abundant in canola (rapseed) oil which is the cheapest source. Most fats quite sensitive to spoilage and should be stored carefully according to instructions. Some cholesterol is ok because it helps the body build hormones including the all important testosterone. Cholesterol can be created by the body without being ingested though and is not “essential” in that sense.
Proteins also have different digestion speeds. Hydrolized or pre-digested whey protein is the fastest to enter the blood. Then there is whey protein, which is moderately quick. Finally casein is a slow digesting protein. There are other kinds of proteins available but these are the most popular protein supplements. Going back to the pillars, remember, the second pillar which is more important comes before this one. It matters much more that you put the protein in your body than what the source of protein is. When you are trying to do a bodybuilding competition everything is going to be extremely fine tuned and it will be necessary to have casein before bed for example but that is an article for another day.
I am not a doctor and this article is offered merely as my opinion from personal experience. You should consult with your doctor before making any changes to your diet and/or exercise programs.