When people want to lose weight, the advice they’ll often get is to simply “eat less and move more.” It’s just calories in vs. calories out, they’ll be told.
But how does that explain the women that come to me at 140, 150, or 160+ pounds, eating 1,300 calories per day, exercising 6 – 7 hours per week…without losing weight?
According to standard calculations, such women should be burning upwards of 2,000 calories per day. So how the hell can they be eating so little without losing fat? And what should they do? Should they suck it up and eat even less? Push through another hour or two of grueling exercise each week? Or is something else needed?
Well, in this article I’m going to break it all down and show you why preserving your metabolic health is the key to consistent, pain-free weight loss.
So let’s start at the beginning: what the hell does metabolism even mean?
The dictionary defines metabolism in the following way:
The chemical processes that occur within a living organism in order to maintain life.
Two kinds of metabolism are often distinguished: constructive metabolism, or anabolism, the synthesis of the proteins, carbohydrates, and fats that form tissue and store energy; and destructive metabolism, or catabolism, the breakdown of complex substances and the consequent production of energy and waste matter.
In short, when we speak of the metabolism, we speak of the body’s ability to use various chemical processes to produce, maintain, and break down various substances, and to make energy available for cells to use.
As you can imagine, this is an incredibly complex subject as it encompasses the entire set of processes whereby life is sustained, so let’s hone in on the aspect of it most relevant to this article: metabolic speed.
Now, what does it mean to have a “slow” or “fast” metabolism?
Well, such distinctions are referring to what is known as the body’s metabolic rate, which is simply the amount of energy the body uses to perform the many functions involved in metabolism.
Basal metabolic rate excludes physical activity, and we often measure it in terms of calories. (One calorie, or kilocalorie as it’s technically known, is the amount of heat required to heat one kilogram of water one degree Celsius)
The faster one’s metabolism is, the more energy the body burns in performing the many tasks related to staying alive. The slower it is, the less energy it burns performing these tasks.
In a funny sense, a slower metabolism is actually more “efficient” than a faster one because it requires less energy to maintain life. (This doesn’t mean a slow metabolism is good.)
Now, the body’s metabolic rate is influenced by various factors such as age, fat mass, fat-free mass, and thyroid hormone circulation, but some people’s bodies also naturally just burn more energy than others’.
For instance, one study reported basal metabolic rates from as low as 1,027 calories per day to as high as 2,499 calories per day, with a mean BMR of 1,500 calories per day. Much of this variance was due to different levels of fat-free mass and fat mass, age, and experimental error, but a significant portion (about 27%) of the variance was unexplained.
Another study demonstrated that basal metabolic rates can vary between people with nearly identical levels of lean mass and fat mass. Researchers found that despite their subjects all having comparable body compositions, the top 5% BMRs metabolized energy about 30% faster than the lowest 5%.
Alright, so that’s what the metabolism is and how it works. Let’s relate it to weight loss.
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As you probably know, you lose fat by feeding your body less energy than it burns every day. Your body deals with this energy deficit, or calorie deficit, by tapping into fat stores to get the energy it needs (that it isn’t getting from the food you eat).
From where are most of these energy demands coming from, though? That’s right, the metabolism.
For instance, a 180-pound man with 10% body fat and a healthy metabolism has a basal metabolic rate of about 2,000 calories per day. Through regular exercise and other activity, total daily energy expenditure could increase to about 2,800 calories per day.
Well, as we can see, about 70% of an in-shape, active man’s total daily energy expenditure still comes from the metabolism.
This is why preserving metabolic health is so important when it comes to weight loss. When you reduce your calorie intake to induce weight loss, you’re counting mainly on your metabolism to keep humming along, pulling from fat stores. Sure, you use exercise to increase overall energy demands and thus fat loss, but your metabolism is a major player in the game.
The slower your metabolism is, the less food you’ll have to eat and the more exercise you’ll have to do to lose weight effectively. The faster it is, the more you’ll be able to eat and the less you’ll have to exercise.
Most people know that losing weight requires eating less food than they’re currently eating and moving more, and most people want to lose weight as quickly as possible.
What do many people do, then? Well, they dramatically reduce calorie intake and dramatically increase energy output (through many hours of exercise each week). And while this approach will induce weight loss for a bit, it will ultimately fail. Why?
Because your metabolism adapts to the amount of energy you feed your body. Its goal is to balance energy intake with output–to maintain homeostasis.
When you restrict your calories and feed your body less energy than it burns, your metabolism naturally begins slowing down (burning less energy). The more you restrict your calories, the faster and greater the down-regulation.
The opposite is true as well, by the way. As you feed your body more, your metabolism will naturally speed up (burn more energy).
Now, when someone dramatically decreases calorie intake and their metabolism finally slows down enough to match intake with output, weight loss stalls. This is usually met with further calorie reduction or more exercise, which only results in more metabolic slowdown, and thus a vicious cycle begins.
In most cases, the dieter finally can’t take the misery anymore, and goes in the other direction, dramatically increasing calorie intake (bingeing and gorging on everything in sight for days or weeks). This, in turn, has been shown to result in rapid fat storage, often beyond the pre-diet body fat levels (people end up fatter than when they started dieting in the first place).
What’s going on here is very simple: these people have systematically crashed their metabolic rates and then overloaded their bodies with way more calories than they needed, and the body’s response to this is to store much of the excess energy as fat.
Ultimately what happens is the person winds up fatter than they started, and with a slower metabolism. If they repeat this cycle a few times, they can find themselves in a really bad place metabolically: eating very little food to maintain a high body fat percentage.
This process of dramatically and chronically slowing the metabolic rate down is often referred to as “metabolic damage,” and fortunately, it can be resolved.
Your metabolic health is going to determine how effectively you can lose weight, so here’s the bottom line:
If you want smooth and consistent weight loss, you want your metabolism to be running quickly before you start.
As the metabolism adapts to food intake, you want your weight to be stable with a high amount of daily calories before you start restricting them for weight loss purposes.
Ideally, you should be eating at least your total daily energy expenditure (TDEE) without gaining weight before you start a weight loss routine.
Here’s a simple calculator that will help you determine your TDEE:
If you’re not currently there–if you’re eating quite a bit less than your TDEE and your weight is not moving, you need to improve your metabolism before you attempt a weight loss routine.
Fortunately, this is easy to do if you remain patient. Here’s how it’s done:
This has two big benefits for your metabolic rate: it speeds it up in the short term, burning a significant amount of post-workout calories; and it builds muscle, which speeds up your metabolic rate in the long term.
In the bodybuilding world, this is known as “reverse dieting,” and it’s a very simple but effective way to speed up your metabolism.
Instead of dramatically increasing your calorie intake, you want to work it up slowly, allowing your metabolism to keep up and match output with intake (resulting in little-to-no fat storage).
I like to increase in increments of about 100 – 150 calories with 7 – 10-day intervals. That is, you increase your daily intake by 100 – 150 maintain that new level of intake for 7 – 10 days. You then do it again and again and again until you’ve reached your TDEE.
I recommend that you eat 1 gram of protein per pound of body weight when you’re working on speeding up your metabolism.
While I’m generally not a fan of high-fat dieting for athletes (and I explain why here), I do recommend eating a fair amount of dietary fat every day when you’re working on improving metabolic health.
I recommend that you get 30 – 35% of your daily calories from dietary fat when you’re working on speeding up your metabolism.
When your metabolism is healthy–when you’re able to eat plenty of food every day without gaining weight–weight loss is very easy.
As discussed in my article on meal planning, you will simply utilize about a 20% calorie deficit with 4 – 6 hours of exercise per week (a combination of weightlifting and high-intensity interval cardio works best), and it will be easy, effective, and enjoyable.
Yes, your metabolism will slow down, but not by much. This approach will give you at least a good 2 – 3 month window in which you can lose plenty of fat while potentially even building muscle.
And if, over time, your metabolism slows down too much but you haven’t hit your body fat percentage goal yet, you simply take the above steps to speed your metabolism back up, and then move back to weight loss.