Energy Balance:

Before calculating macronutrients (macros), calorie needs, etc., it’s important to understand the mechanism which drives fat loss and factors which influence it. Energy (Calories or kilojoules) will dictate fat balance. Fat balance can be viewed as the simple math equation of energy balance = energy consumed – energy burned. Although a bit simplistic, energy balance will determine how much fat you’re gaining (if your energy balance is positive) or how much fat you’re losing (if your energy balance is negative).

So where do calories come from?

There are only 3 (with an additional caveat) nutrients which contain a significant amount of energy:

• Carbohydrates: 4 calories per gram
• Protein: 4 calories per gram
• Fat (lipids): 9 calories per gram

The 4th case is a topic of debate within nutritional science, as alcohol contains 7 calories per gram, although it’s commonly not thought of as being a nutrient, as it doesn’t serve any biological needs aside from calories themselves. For the intent of this resource, I would just be aware that alcoholic beverages do contain calories, so be cautious of the calorie content if you’re someone who consumes it.

Where does 3500 calories = 1lb of fat come from?

Our body will primarily store excess energy in adipose tissue (body fat), which also contains 9 calories per gram. There are 454 grams in 1 pound, which when multiplied by the fat content, comes towe get 4068 calories. Human adipose tissue tends to contain around 15% water and organelles, which we factor out of the equation, leaving us with around 3500 calories. This number is actually not all that exact, so you shouldn't worry about creating the "perfect" calculation for a specific rate of fat loss.

While all of this may seem trivial, this is the very foundation on which every factor pertaining to fat balance must adhere to. Whether you’re doing intermitting fasting, carb cycling, keto, carnivore, a well-rounded diet, etc., any changes in body fat will be entirely attributed to the energy balance of how the diet is applied. With that in mind, you can achieve fat loss with an infinite number of approaches (even with a conventionally “unhealthy” diet), which is why the cliché of adhere being so important actually holds true.

Macros:

If energy balance is all that matters for fat loss, why do we care about specific macros?

In the Energy Balance section above, I mentioned that energy balance can be a bit of an overly simplistic calculation for determining precise fat loss outcomes. The main caveat of energy balance not always being perfectly predictive of fat loss comes from the fact adipose tissue is only one form1 of the human body’s form of energy storage in the human body. Typically, when we’re seeking “weight loss”, we’re actually seeking “fat loss”, which makes us worry more specifically about protein intake. Under-consuming protein, especially while in an energy deficit, will lead to proportionally more muscle mass loss compared to higher protein diets. Whether you’re looking to lose body fat, maintain, or gain body fat, consuming adequate protein will ensure your body is favoring adipose tissue rather than muscle mass. This isn’t to say more is better, but the threshold of around .8-1.0 grams of protein per pound of bodyweight is a good goal to aim for.

What about fat and carbs?

Although dietary fat and carbohydrates serve their own function for overall wellness, under normal circumstances, when you equate the overall calorie, they can be used interchangeably without any significant difference in either fat loss or muscle gain[1]. Although this may be a bit confusing, this ties back to the first order principle of energy balance – whether the calories are coming from fat, protein, or carbohydrates, anything excess will ultimately be stored in the body.

Calculating Your Needs:

Before using the calculator below, it's important to put it into a larger context. An energy and/or macro calculator is nothing more than a tool to provide a general guideline for your needs.

I would strongly urge you to NOT take this (or any other) calculator as being the “perfect” calorie goal for you. Depending on your goals, fat loss can be a very lengthy process (if you were to eat in a 500 calorie deficit, you would lose about 1lb of body fat per week). Focus on precision (reproducibility) rather than accuracy, aiming to hit within 10% of your target values. Nutritional success will come entirely from a good trend of precision (accepting not every day will be perfect), self-monitoring your progress, and making small adjustments based on how your trends and goals – all of this will be covered in a future post!

Which one should you use?

Both calculators follow the same formula for calories and protein, which is of utmost importance for body composition. I recommend picking the one which you believe will be easiest to adhere to, experimenting around with both. If you’re newer to tracking, dieting, etc., you might find it helpful to actually track macros instead of calories, as paying attention to each value will require a bit more caution and planning, which tends to increase precision of landing in a good general ballpark of your calories.

What if these recommendations seem off?

Calculators are based off of averages and can’t fully factor in your lifestyle, so it’s possible these calories aren’t ideal for you. If you’re entirely new to tracking calories, I would stick to what the calculator says for 1-2 weeks and take note of your change in weight, appetite, etc., then make changes accordingly. If you have experience tracking and these numbers seem off, I would favor them based on your own historical data (your energy intake and your biometric trends).