metabolism - FIT & NU™

The science behind why it’s so hard to lose weight.

Smart scale and measruing tape
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At the beginning of each year, millions of Americans make a New Year’s resolution to lose weight, often through some sort of crash-course dieting plan. However, they also tend to learn that losing weight is much harder than they thought it would be. Or, more commonly, they immediately gain the weight right back once they stop dieting. Have you ever wondered why that is or are you one of the millions of people struggling with weight loss?

A lot of this can be explained by what happens to our metabolism when we lose weight, especially when we shed pounds quickly. Read on to learn more about the biology behind weight loss and 3 tips on how to counteract our bodies natural tendencies.

Rapid Weight Loss Can Slow Metabolism

If you find this counterintuitive (and frustrating), you’re not alone. If more people knew about this, the diet industry would be out of business. Before we dive deeper into what is going on, let’s break down what metabolism is.

What is metabolism and how does it work?

Metabolism is basically the way that our bodies convert the food that we eat into energy.

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Our bodies are constantly expending energy. Whether we’re readjusting our position in a chair or engaging in rigorous exercise such as running or cycling, our bodies need energy to power every movement we make.

We also use energy for activities that don’t involve physical activity, like sitting still and thinking. In fact, researchers found that the brain accounts for 20% of our energy consumption, despite only representing about 2% of our total body weight. Overall, cognitive activities account for most of the energy that our bodies use, through a process (60%-70%) driven by what is referred to as our Resting Metabolic Rate (RMR).

Beside the energy used through RMR, an additional 10% of energy is used to digest food, and the remaining 20%-30% is expended during physical activities.

Keep in mind that these statistics are also estimated averages. If you’re an athlete or have certain health conditions, these numbers will look different. For example, an underactive thyroid gland (hypothyroidism) can slow the metabolism. If you have any weight concerns related to your metabolism, you should consult with a medical doctor. They may decide to assess your thyroid hormone levels. If it is low, you may be prescribed a replacement thyroid hormone. You can learn more by reading this summary, published by the University of Rochester Medical Center.

How does metabolism affect our weight?

Our weight is the outcome of the energy that we consume and the energy that we use. Weight gain occurs when we take in more energy than they use and weight loss occurs in the reverse. So it might make sense to dramatically cut down calories or begin exercising a lot more and a lot longer each day to quickly lose weight.

As we’ve discussed previously, the problem is that our bodies are equipped with a powerful, natural defense system to counteract this type of extreme dieting approach. When we eat dramatically less (especially for more than a couple of days) our bodies interpret this as starvation and it begins sending out signals to conserve more energy.

One critical way that our body will attempt to conserve energy is by eliminating anything that takes a lot of it, such as lean muscle tissue which also has downstream effects for metabolism.

It’s also worth noting that rapid weight loss also throws our hormones out of whack. There are several hormones involved, but one of the most well-researched is leptin which signals to our brain that we are full and to stop eating. As our bodies lose weight, we also decrease our levels of leptin and without that signal (or less of it) we want to eat more, even if our body is consuming less energy.

Is There A Solution?

Yes! Healthy habits.

Head Fitness Coach and Co-Founder of FIT & NU, Brittney Rae Reese
Head Fitness Coach and Co-Founder of FIT & NU, Brittney Rae Reese. Photo by Andrea Gerstenberger

If you’re new to our blog or just now being introduced to our work, healthy habits are at the heart of our wellness philosophy. You may be interested in reading our tips for dumping those all-or-nothing diet routines and 6 small steps you can take right now to make big changes to your health.

Basically, there are a lot of things working against us, from our busy professional and personal lives to the powerful biological forces that can sometimes undermine our desires and efforts to manage our health. The only way to overcome this type of gravity is through small and consistent behavioral modifications that will eventually snowball and take on a momentum of their own. Read some of our previous posts if you need a refresher, like those 6 tips I just mentioned.

Here are 3 more tips to keep you motivated and those healthy habits on track:

1. Celebrate any success like crazy, no matter how small.

Whether you hit your goal to run an ultramarathon or you managed to lay out your workout clothes, dust those shoulders off and congratulate yourself for being the rockstar queen that you are!

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2. Feeling stuck or indecisive? Ask yourself “What would a healthy person do?”

A common example is deciding on what to order at a restaurant. When browsing through the menu of options, try asking yourself, “What would a healthy person do?”

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This will help orient your attention to more nutritious meal options like a salad and away from other temptations like a burger and fries. You can also gain greater control over your relationship with food through mindful eating, which we’ve written about previously here. Eventually, you won’t have to ask yourself this question anymore because these choices will become instinctual. Plus, you will start to associate yourself as the healthy person.

3. Incorporate some form of physical movement in your day.

Even if it means pacing around your room for 20 minutes while you phone a friend, physical activity improves your mood and sleep, while reducing stress and blood sugar levels. Additionally, while it isn’t the biggest factor in losing weight, exercise is key to maintaining the weight that you want to be.

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The key point to takeaway is that our eating behaviors have the greatest affect on changing our waistlines, while exercise helps us maintain those changes. Crash-course diets impact both but those changes tend to be temporary and short-lived. We need to establish healthy habits, if we want long-term sustainable results.

NOTE: This blog post was also published on Medium.

Editor’s Note: The initial post incorrectly attributed the third photo to Blake Jackson. The caption has since been edited to credit Andrea Gerstenberger.