If It Fits Your Macros (IIFYM)

Weight Gain and Weight Loss

When it comes to weight gain and weight loss, everything boils down to a simple equation:

Calories Ingested – Calories Expended = Daily Gain or Loss

e.g. If you eat 2,000 calories in a day, but only burn 1,800 calories throughout the day, then you're left with +200 calories. If you did this every day, then you could expect to weigh more in the long term.

The two primary elements that make up your “Calories Expended” category include:

  1. Your Metabolism (the number of calories your body naturally burns in order to function)
  2. Your Daily Activities (calories burned from work, fitness, doing chores, etc.)

Let’s assume your goal is to lose 5 pounds. It's important to consider that it is “unhealthy” to lose more than 2 pounds per week. Doing so will result in muscle atrophy (muscle and strength loss). In fact, it's similar in the opposite direction, as gaining weight too quickly will result in the addition of mostly fat and water weight.

Let’s also assume that your metabolism naturally burns about 1,400 calories per day, and your workout plus daily activities burn another 600 calories.

Calories Ingested – 2,000 Calories = Daily Gain or Loss

To keep yourself at a safe rate of weight loss, and for simplicity, we want your Daily Loss to be roughly 100 calories.

Calories Ingested – 2,000 Calories = -100 Calories

Calories Ingested = 1,900 Calories

Obviously, trial and error is needed to determine your daily Calories Expended. The best way to find your current rate is to weigh yourself one morning, track the number of calories you eat that day, weigh yourself the next morning, see if you went up or down, and adjust your calories until you're the same weight as the day before. Ideally, you will operate off of an average weight over several days to avoid making drastic (and unwarranted) changes.

Now let’s assume you continue at -100 calories per day as your Daily Loss (this translated to a rough average of -0.2 lbs per day for me). After about a week, your metabolism will slow down in order to adjust to this daily loss (it’s a basic survival mechanism). This means that you will now need to eat less if you want to keep losing weight. To do so, drop your daily Calories Ingested by about 100 calories. You will need to continue this trend until you reach your desired weight. If you're eating too little and can no longer safely drop calories, then you'll need to add more to your workout. Be careful if you get close to this point. You can also use these principles to speed up your metabolism and gain weight.

Macro Nutrients and Micro Nutrients

To kick things off, we first need to set the record straight:

  • “Super foods”, fad diets, etc. are largely dishonest schemes to get your money (some diets work better than others based on people’s preferences, but everything boils down to the information outlined in the “Weight Gain and Weight Loss” section)
  • The number of meals you eat, and the times that you eat them, largely do not matter
  • You will get most of your necessary micro nutrients through the food you eat (a simple multivitamin should cover the rest if you don’t eat a lot of “healthy” foods)

The point here is that your primary concern in terms of manipulating your weight should be macro nutrients (protein, carbs, and fats). Here's how they break down on a calorie-per-gram level:

  • Protein = 4 Calories/Gram
  • Carbs = 4 Calories/Gram
  • Fats = 9 Calories/Gram

Let’s say you have grilled chicken with BBQ sauce. We will assume it’s 25 grams of protein, 8 grams of carbs, and 1 gram of fat.

  • Protein = 25 x 4 = 100 Calories
  • Carbs = 8 x 4 = 32 Calories
  • Fats = 1 x 9 = 9 Calories
  • Total = 141 Calories

So how much of each macro nutrient do you need per day? You probably don’t weigh this, but let’s say you weigh 127 lbs (I outlined this section in the past for a girl who weighed that, so I’m going to be lazy and leave it). Here's a baseline for what you would need to eat so that you don’t lose a lot of muscle and/or die:


For women, multiply your bodyweight by something between 0.6 and 0.8 (we will avoid too much nuance and go with 0.7). 127 x 0.7 = 88.9. Rounding up, you need to eat at least 89 grams of protein per day to avoid unnecessary muscle atrophy. This means that you will devote 89 x 4 = 356 calories to protein each day at a minimum.

For men, you will want to multiply your bodyweight by something between 0.8 and 1.2. Men have a greater proportion of lean body mass, and thus need more protein per pound of body weight. I personally try to hit the 0.8 number at a minimum, and then anything else is a bonus. You don't gain much by ingesting more unless you take performance-enhancing drugs.


This is a little bit trickier, and I like to play it safe. Fats are necessary in order to maintain healthy body functions and hormonal balances. Women generally need more than men, but anything over 45 grams per day should be safe (you can go lower and be ok, but I don’t want to say it’s ok to stay lower for a long period of time). This means that you will devote 45 x 9 = 405 calories to fats each day at a minimum.

Men generally need less, but should try to stay above 25 grams or so per day. Others use percentages of total calories consumed to track fat intake, so you may see suggestions such as 20% to 35% of total calories devoted to fat consumption.


LOL you don’t actually need carbs in order to live! That said, they give you energy and taste delicious. Feel free to fill your remaining calories with carbs. In this example, you are spending 356 calories on protein, and 405 calories on fat (761 Total Calories). Have fun with the rest of your calories! However, make sure to get enough fiber per day. I usually eat something like a low-calorie fiber brownie in the morning to cover it.


The main point is that you can eat what you want as long as you hit your macros. Yes, your body will react differently to different foods, but what's outlined here is all your body needs to function properly and safely. Eating 500g of sugar for your carbs may make you feel a lot worse than taking a balanced approach, but you'll have the same end result as long as you track your calories and macros. For example, I regularly ate ice cream while cutting over 30 lbs in college.

The primary downside to this approach is that you need to weigh your food for accurate results. If you eyeball everything, you can still make progress, but you risk prolonging the process and experiencing setbacks.

For more on nutrition, I recommend www.biolayne.com. Layne Norton is a tremendous resource for nutrition and exercise science, and stays more up-to-date on information than I do (this is his world). He has a wealth of free material to explore. IIFYM (If It Fits Your Macros) is a great tool to implement in your daily life. It will help you maintain your desired body image, and limit cravings that tend to develop when specific foods are purposely (and unnecessarily) avoided.

You can follow my fitness journey here


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