Guest Post: How Genes Affect Weight

It’s with great excitement that we welcome Kristen Whittington of Unconditional Nutrition for our first ever guest blog author! Read on for her insight on how genes affect weight more than you think.

I thought health was as simple as eating the “right foods” and exercising enough. In college I restricted my intake, exercised as much as I could, and when I couldn’t hold out any longer I would binge. I did this all in the name of health and in order to have that perfect body. You know the one. You’ve seen it on TV and in movies. The body you have to have to enjoy your life, deserve love and respect, and to be healthy. At least, that’s what our culture tells us. There’s one pretty glaring flaw in this whole narrative though. This narrative is based on the underlying assumption that you can control your body weight and shape. That’s what were told and sold. This is false. But no one tells you that. I learned this as part of my unlearning process when I was seeing a dietitian for my own disordered eating and throughout my professional development to become a dietitian.

I know what you’re thinking, “But, Kristen I know people who have lost weight/changed their body! It can be done!” To that I will say, I’ve heard of and seen those people too and most people who lose weight, regain that weight in 2-5 five years. The idea that you can change your weight permanently and long term is about as futile at the American dream.

Years of evolution, biology, and your own genetics are stacked against you. This is both freeing and jarring. If we don’t have ourselves to beat up about how we don’t have the right body, what do we have?!

Here’s the dirty little secret I learned while I was in my graduate program: you don’t have as much control over your body weight and shape as you’ve been told you do. We have an opportunity to let this free us from the fixation on weight we’ve been trained to have so we can focus on an approach to health that makes us feel good, not guilty.

The science behind energy consumption.

Let’s start with what makes up the energy you need be a person every day. There are four components to the energy you use every day (and night): your resting metabolic rate, the thermic effect of food, non-exercise associated thermogenesis (NEAT), and thermogenesis from activity.

Your resting metabolic rate is your baseline how much energy you need to stay alive. This includes breathing, thinking, sending nerve signals, using your muscles to exist, your heart beating, etc. This makes up anywhere form 66-75% of your energy needs. So, already we can see that exercise you do intentionally makes up less than a quarter of the energy you use in a day. The combination of the thermic effect of food, NEAT, and thermogenesis from physical activity make up the remaining 25% of your energy expenditure.

The thermic effect of food is the energy you use to break down the food you eat. This is minimal. NEAT is all the things you do throughout the day that is not intentional exercise but is still activity. Walking from your car to the grocery store, putting your clothes in the dryer, loading the dishwasher, stuff like that.

And finally, thermogenesis from intentional physical activity. This at most accounts for 15% of your energy needs in a day.

Your genetics determine your resting metabolic rate.

Here’s the kicker: your genetics determines your resting metabolic rate. The thing that makes up 66-75% of the energy your body uses in a day is determined by your genes. You have no control over that. You know what else is determined by your genes? The size and number of fat cells in your body, and the way that fat is distributed. I’ll repeat that. Your genes determine the number of fat cells in your body, where those fat cells are distributed, and the size of those cells. So, why are there a million different diets out there trying to get you to change something that at most will vary by 25%? Why invest the time, the money, the deprivation, the disappointment? 

If the fact that your genes determine a majority of your body shape and size hasn’t convinced you let me tell you a little bit about how the body responds to deprivation of food and increased exercise.

Before we dive in, I want to acknowledge what a well programed machine the body is. Over thousands of years it has adapted fail-safes to prevent us from starving to death. It doesn’t know anything about the latest body size or shape that is trendy, its main function is survival and it is damn good at keeping us alive.

The mantra of any and all diets is “calories in calories out.” You can either decrease the calories in (decrease the food you eat) or increase the calories out (increase your activity), or do both! When you restrict calories your body temporarily decreases your resting metabolic rate to conserve energy. When your resting metabolic rate goes down you need less food to fuel your body. This helps explain the why you see initial weight loss and the regain weight when you stop restricting. These self induced weight fluctuations are called weight cycling.

The cons of weight cycling.

Weight cycling has actually shown to be harmful to your long term health. Unfortunately, when you lose weight you usually lose both muscle and fat. Your body takes energy stores from both your muscle and fat. Not just fat. When you regain weight, you’re mostly gaining back fat, not muscle.

There is a theory that your body favors weight gain until you regain all of the muscle you lost when you lost weight initially, but that fat is preferentially stored. So, it takes longer to regain the lost muscle and in the meantime you are regaining fat. This explains why some people regain more weight than they lost and can, over continuous cycles of weight loss and regain rachet up the point at which their weight tends to settle. Their settling point. When you have a healthy relationship with food and exercise and are not intentionally trying to manipulate your weight, it settles within a certain range. This range can be disrupted by years of weight cycling, dieting, and disordered eating and changes as you age.

What is my approach to diet and health?

That’s what I learned during my training to become a dietitian. We have so very little control over our body shape or size and yet that is the thing we are told to focus on the most. We use it as a measure of our health and our progress. But, what if, instead of focusing on weight as a measure of your health, you shifted the focus to your relationship with food and exercise? What if you considered how your relationships, work, stress, and sleep contribute to your health? I can guarantee that when you start to let go of weight as your indicator of health and wellbeing your world begins to open up. Navigating that process alone is tricky. If you’re up for the challenge, I recommend working with a dietitian, like me. I do one on one nutrition counseling and practice from a weight neutral, non diet perspective. Check out my website and Instagram for details.

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