Being healthy is simple, right? “Eat less, move more.” That’s easy to say, but practicality is one of the most important things when it comes to health and fitness. Recommendations like this are blanket statements that don’t address practicality—so when it comes down to it, which is more important? Diet, or exercise?
Yes, we should all eat healthier. Yes, we should exercise every day. There are infinite things we could do in order to be healthier, like sit less, eat more vegetables, eat less processed food, or drink less alcohol. But they don’t take into account the reality of life: we are all constrained by a finite amount of resources such as time, energy, willpower, and money. Recommendations that don’t take this into account can easily make us feel like we are failing our fitness and health goals.
A Primer on Calories
At a physiological level, weight loss and weight gain revolve around caloric consumption and expenditure*. Because of this, it’s important to understand the basics of calories. Put simply: we lose weight when we eat less calories than we expend. Conversely, we gain weight when we eat more calories than we expend. In order to lose one pound of fat, we must create a 3,500 calorie deficit, which can be achieved either through exercise or diet.
*As an aside, it’s worth noting that some argue that carbohydrates and insulin are the culprits behind weight loss and weight gain in what is called “the insulin hypothesis of obesity.” While controlling both carbohydrates and insulin may be important for some individuals, this hypothesis has been thoroughly debunked.
Let’s say that a 200 pound man wants to lose one pound in a week. Through exercise alone, he needs to run about 3.5 miles per day (or 24.5 miles total), assuming his diet stays the same. Through dieting alone, he needs to cut back 500 calories/day (the equivalent of two Starbucks Frappuccinos), given his exercise regime stays the same. Theoretically, the two should achieve the same results.
But in the world of fitness theory and reality are not the same thing, because theory does not account for adherence. We don’t live in a magical house that contains a gym, a Whole Foods, and a personal staff of nutritionists and trainers. Instead, we’re left about our own devices in everyday life. What happens then?
Why Exercise-Focused Regimens are Relatively Ineffective for Weight Loss
If you’re perplexed by the information above, don’t worry. There’s a simple explanation behind it, which we’ll break up into two parts
Reason 1. Calorie expenditure through exercise is relatively small in the grand scheme of things.
In order to see why exercise-focused weight loss programs might yield low efficacy, it’s important to understand the accounting behind our daily caloric expenditure.
We spend most of our calories every day just “staying alive.” This is known as our “resting metabolic rate.” The Katch-McArdle formula, which takes into account one’s body fat percentage, is the most accurate way to calculate this number, which is equivalent to:
9.81 x your amount of non-fat mass + 370 calories per day
Let’s say you are a 200 pound man who is at 30% body fat. You expend 1,743 calories per day just staying alive. (200 x (1-.30) * 9.81 + 370 calories)
He’ll expend about 10% on top of that by what’s known as the Thermic Effect of Food (TEF): the amount of calories that he spends digesting and absorbing his dietary intake.
Add another 10% on top of that through a metabolic process known as NEAT ( Non Exercise Adaptive Thermogenesis). This is the amount of calories wasted through things such as fidgeting. Unfortunately, this can vary greatly from individual to individual.
This means that without so much as getting out of bed, our subject has already expended 2,100 calories.
Now, add another 10% for getting out of bed and going about his daily routine and he’s already burned 2,300 calories.
Adding exercise into the equation barely makes a dent in his overall caloric expenditure; most of the work is done before he puts on his running shoes. Now I am not saying that you shouldn’t exercise, but rather, it’s important to realize where a majority of your caloric expenditure is coming from. You wouldn’t take up a paper route in order to supplement a 100k/year salary, would you?
Reason 2. People are horrible estimators of calories in vs. calories out.
Take a look at another study, this one in the Journal of Sports Medicine and Physical Fitness, in which researchers asked the subjects to exercise, estimate their caloric expenditure, and then took them to a buffet afterwards. Subjects were asked to consume the amount of food that they believed they burned in calories. (Sidenote: Where can I sign up for one of these?)
The subjects ended up eating 2-3 times the amount of calories that they burned.
The takeaway from all of this information is that calorie expenditure doesn’t count for much, and human beings are generally terrible at estimating both expenditure and intake.
Where to Go From Here
k, so I’ve given you a lot of information suggesting that exercise, as the sole means of creating weight loss, is relatively inefficient or even counterproductive. Here are the steps that you should take to best ensure your success.
Determine how many calories you expend every single day. You can use ExRx’s calculator here. For best accuracy, calculate this by body fat percentage. If you don’t know your current body fat percentage you can use this helpful article by Leigh Peele.
Reduce your calorie intake by 20% of your maintenance calories. Any time you decrease your caloric intake, it’s helpful to simultaneously increase your amount of protein in order to stay satiated. (Protein also has the higher Thermic Effect of Food out of any macronutrient, meaning your body needs to expend more energy to digest it in comparison to carbs or fats.)
How much protein should you be eating on a caloric deficit? Nutritionist Alan Aragon recommends figuring out your target body weight and getting that amount in grams. For example, if you are a 200 pound woman who wants to get down to 120 pounds, consume at least 120g of protein per day.
Once you are comfortable with counting calories, consider switching to counting macronutrients instead. Focusing on macronutrients, rather than calories calories, is a nice “hack” to disrupt the fact that people (myself included) are often translating exercise and eating into the same currency: calories. You can learn all about the basics of how to count macros here.
You’ll notice that the weight loss recommendation above makes no mention of exercise. But while you shouldn’t be factoring exercise into your caloric expenditure or intake, you should still be incorporating it as much as possible practical.
“Sure, weight is lost in the kitchen,” says Dr. Freedhoff. “But health is gained in the gyms.”