“I’m not losing any fat! I think my metabolism is in starvation mode!”

If I had a dollar for every time someone said this to me, I’d be doing this for days;

I get it though. I’ve had many clients who have been doing excellent with their eating habits but have suddenly stopped their fat loss progress with no logical explanation why. Nothing is more frustrating than doing all the right things and not seeing the results you want. Eventually, that frustration can lead you to relapse back into old, unhealthy eating habits like this;

Recently, I’ve been noticing that some “experts” are blaming the fact that your body is in “starvation mode” or that your metabolism is slow. While it makes sense in theory, is this the case though? The purpose of this blog is to answer that question. Is your lack of fat loss due to your slow metabolism or “starvation mode”? Before we answer that question, let’s get some background on what makes up your metabolism, how metabolism varies from person to person, and what can affect metabolism.

What is metabolism?

Human metabolism is made up of four components;

Basal (resting) metabolic rate (BMR or RMR): This refers to the calories you burn just being alive. This makes up about 60-70% of your metabolism. Just the act of breathing burns calories. I mean, look at how many calories this cat must be burning right meow.

Non exercise activity thermogenesis (NEAT): This refers to the calories you burn that isn’t intentional exercise. These activities range from fidgeting, walking, yard work, etc. This accounts for roughly 30% of total energy expenditure but it varies from person to person depending on how active your job or daily life is.

Exercise activity thermogenesis (EAT): This refers to the calories you burn during intentional exercise. This accounts for roughly 10-15% of your total energy expenditure but can greatly vary depending on what type of exercise you do and how long you do it for.

Thermic effect of feeding (TEF): Lastly, this refers to the calories you burn digesting food. Yes, you burn calories eating. This accounts for roughly 5-10% of your total energy expenditure.

How different is metabolism from person to person?

There are a few ways that metabolism can vary from person to person. The biggest factor that accounts for these differences is NEAT. For instance, if you took two people who had identical height, weight, and age but one works construction (or some other labor intensive job) and the other works a desk job (mostly sedentary), you’ll most likely find that the person who works in construction has a higher metabolism.

In addition, differences in body composition factors into one’s metabolism. For instance, if you took two people who again had identical height, weight, and age but one was 10% body fat and the other was 25% body fat, you’ll find the person who had lower body fat has a higher metabolism. This is due to the fact that muscle burns roughly 6 calories per lb/day while fat burns only 2 calories  per lb/day.

Lastly, genetics can play a role in how fast one’s metabolism is, but no one is really sure why.

Can dieting affect your metabolism?

Yes, dieting can in fact cause your metabolism to slow down. Let’s think about it. When you diet down, the goal is to reduce your body weight. Reducing your body weight also reduces the amount of calories your body needs each day. Makes sense right? This process is called adaptive thermogenesis. As you get leaner, your nervous system becomes more conservative and efficient with energy expenditure in order to prevent starvation.

So how much does your metabolism actually change when dieting down? It turns out, not as much as you think. This study found that basal metabolic rate only changed by about 10-15%.  What accounted for the majority of the reduction in metabolism came from decreases in NEAT, not BMR. Simply put, as you diet down and your metabolism begins to adapt, you start to move less to conserve energy.

 

Before we move on, I want to clarify one thing. Adaptive thermogenesis is not the same as starvation mode. Let me give you an example of what starvation actually is. Back in 1944-1945, researchers carried out the Minnesota Starvation Experiment. 36 men were put on a 24-week long starvation diet that consisted of two meals that equaled 1560 calories per day. Their calorie intake was then reduced further as the study went on to keep weight loss happening

On top of a low calorie intake, they were also expected to walk or run 22 miles every week. This added up to roughly  a 50% deficit. Side note: General guidelines for the most aggressive fat loss protocols are 20-25%. This was twice that amount. In the end, all the men lost about 25% of their total body weight and ended up around 5% body fat. By the end of the study, the men’s metabolic rates dropped by about 40% but their actual BMR only dropped by around 15%.

Unless you are planning on repeating those conditions when you are dieting (I certainly hope you won’t), you don’t have to worry about being in starvation mode.

“If it’s not starvation mode, then it has to be because of my slow metabolism!”

As you can see, metabolism does in fact vary from person to person and can be affected by dieting. It makes sense to think that maybe your metabolism is significantly slower than the average person and that’s why you have a harder time losing fat. Is the variation in metabolism from person to person really that significant though? Here’s the answer:

Let me explain. The variation in resting metabolic rate from person to person is only 5-8%. This amounts to a difference of only 200-300 calories. That’s roughly 2 tbsp of peanut butter or one pop tart. That’s really not as significant as you think.

“Well if my body isn’t in starvation mode and my metabolism isn’t significantly slower than someone else’s, why am I not losing fat?”

That’s a great question. Here are two things to look at that can be getting in the way of your success.

  1. You have not accounted for the change in your metabolism: Like I mentioned above, as you diet down your calorie needs change. If you aren’t accommodating this change, you will most likely find yourself stuck at the same weight.
  2. You are misreporting your calorie intake: This is fairly common even amongst nutrition professionals. We are notorious for under reporting our calorie intake and over reporting our activity levels.

What can you do if you want to improve your metabolism?

After all of that, if you are still convinced that your metabolism is to blame for the lack of your success, here are two things you can do to improve it.

  1. Incorporate resistance training: Like I mentioned above, the more lean mass you have, the more calories you burn. Resistance training is the best way to increase lean mass.
  2. Increase NEAT: Being more active throughout the day can help increase the amount of calories you burn.

By incorporating those two strategies, it will hopefully give you the peace of mind that you are doing everything you can to keep your metabolism humming along.

 

Want more information about nutrition counseling or our Fuel program? Contact one of our registered dietitian nutritionists today!

 

Written by: Jesus Hernandez RDN, LD

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