Maintaining weight loss: The importance of metabolism

Years of evidence shows that diets, in the traditional sense of the word, do not work because the weight loss is generally not sustainable. You motivate yourself to diet, you work hard to remain disciplined, you lose the weight you want, success! 3 months later… the weight is back. At Habitual, we believe that maintaining weight loss requires taking a more holistic view—one that includes everything from sleep to stress levels, and importantly, metabolism. Before we dive into that, let’s take a closer look at how dieting actually works.

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How does dieting make you lose weight initially?

The underlying premise of most diets involve calorie restriction. Even diets which claim not to focus on calories, but rather food groups (such as low carb diets) tend to have the effect of lowering overall calorie intake.

The below formula is what many doctors, healthcare systems, and individuals believe to be true about weight and dieting.

Energy In (what we eat, in calories) - Energy Out (the energy our bodies consume in our day-to-day lives) = Energy Stored (and the reason for weight gain)

In a very general sense, this is true. The takeaways from the above formula include:

- When you eat more calories than you burn, you will store energy in the form of weight gain
- If you want to lose weight, you’ll have to consume fewer calories than you burn

From a purely scientific perspective, this makes sense. But… it’s not so simple in reality. Too many factors are at play. Mood, sleep, stress, exercise, environment, temptation, and psychology all affect success in dieting, to name just a few. The formula also assumes that every calorie is the same—that is, 100kcal of chocolate is the same as 100kcal of broccoli. And another crucially invisible factor? Metabolism. Next, we’ll take a look into how diets affect our metabolism.

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What role does metabolism play in weight loss and weight maintenance?

When we talk about metabolism, we are actually talking about the Basal Metabolic Rate, or BMR, which is the number of calories your body burns just by being alive. Effectively, it is the number of calories you would burn if you were to lay in bed all day. BMR tends to be (counterintuitively) higher for heavier people, as the more body there is to move, the more energy it takes to do so.

Reassessing the previous section’s formula (Energy In - Energy Out = Energy Stored), people often assume that the “Energy Out” number depends mostly on how much we exercise. In reality, however, our BMR is the much more impactful piece of the puzzle: You might burn a few hundred calories doing intensive exercise, but the average person usually has a BMR of between 1400-1800 calories. Therefore, differences in BMR lead to two people, with the same weight, on the same exact diet plan, losing weight at different rates.

You might be asking, what affects my metabolism? Here are a few factors, some of them in our control and others unfortunately not:

- Age: Metabolism slows with age due to muscle to fat ratio, hormonal, and neurological changes

- Genetics: Genetically people have different natural rates of metabolism

- Environmental Factors: Extreme temperatures (both hot/cold) can cause metabolism to increase

- Muscle to Fat Ratio: Muscle tissues burn more energy than body fats

- Exercise: Creates more muscle, increasing your metabolism

- Sleep: The better and longer you sleep, the more consistent your metabolism

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Does losing weight reduce my metabolism?

You may have heard that dieting slows down your metabolism. There is indeed evidence of this in the scientific literature, though it’s worth noting that this would be expected, as a smaller body will require less energy.

Some diets may also lead your body to break down muscle to use for energy. Muscle tissues burn more energy than body fats—so if you reduce the muscle-to-fat ratio in your body, you’ll have a lower BMR.

The problem, however, tends to occur when someone goes off of a diet, and resumes old eating habits—the habits that were designed to feed the heavier body.

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So… is a lower metabolism to blame for weight regain?

The answer to this question is that it’s metabolism plus a plethora of other factors.

Yes, a lower BMR as a result of dieting means that your body will burn fewer calories than before. For example, let’s suppose your BMR dropped from 1,600 to 1,400 due to weight loss from a diet: When you go back to old ways of eating, that’s the equivalent of eating 200 calories more per day!

But the likely more significant issue is the return to old eating habits. If you were eating, let’s say, 2,500 calories per day, then started restricting it to 1,500 during a diet, then returned back to 2,500 per day, it’s no surprise the weight regain comes quickly.

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How can you maintain weight loss after a diet?

1. Whichever diet you are on, you need to have a phased reintroduction of food. This stepped food reintroduction can help you find your “new normal”. Rather than jumping straight back into old eating habits with a dampened metabolism, this slow ramp back into a normal diet allows you time to adjust—both mentally, to a healthier and more sustainable diet, and physically, to a lighter body with a metabolism that reflects your new size. To give you a sense of how important we think this, at Habitual, we spend the same amount of time on food reintroduction (3 months) as we do on the actual TDR diet (3 months)!

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2. Sustaining any change in life requires holistic change. Maintaining a healthy weight is no different. Our metabolisms (and therefore our ability to maintain a healthy weight) can be impacted by sleep, stress, different foods, exercise…. You name it! That’s why we need to dedicate as much time building our understanding of these factors as we do on learning about how to eat well. In fact, at Habitual, we like to spend the majority of our time learning about these aspects, because we believe that’s where a sustainable, healthy weight is built.

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3. Another critical factor is exercise, which helps to increase muscle mass – and more muscle means a higher metabolic rate. As we learned about, this means you’ll burn more calories without exerting any extra effort! So interestingly, whilst most people think exercise is important because it burns calories, this is actually of lesser importance; exercise’s main function in weight maintenance lies in the impact it has on our metabolism.

Ultimately, maintaining the weight loss you’ve worked hard to achieve requires taking a holistic perspective, where your identity based habits around factors such as sleep, food, and exercise, reflect the person you are becoming, not the person you used to be. You can read further about how identity based habits can create holistic change here, and tips for creating new eating habits here.