There are several ways to determine your resting metabolic rate (RMR) — the number of calories your body burns at rest to carry out typical body functions like breathing and pumping blood. RMR makes up a large part of your metabolism — the total number of calories you burn in a day.
The traditional way to measure RMR is to use a standardized formula that factors in your sex, weight, height and age. One of those formulas is known as the Harris-Benedict equation:
- For women, 655 + (9.6 x weight in kilograms) + (1.8 x height in centimeters) – (4.7 x age in years)
- For men, 66 + (13.7 x weight in kilograms) + (5 x height in centimeters) – (6.8 x age in years)
That will tell you how many calories the average person of your age, height, and weight burns at rest in a day. You then have to add on calories you burn with activity (like working out, walking, etc.)
But if you don’t feel like doing all that math and converting to centimeters and kilograms (if you are an American like me), there are also easy to use calculators on teambeachbody. Just log in, click “Get Fit”, then “Fitness Tools”, and you’ll see the “Caloric Needs Calculator”.
However, with any of these methods, the results may not be very accurate for you. Formulas like this one are based on average people, and all of us aren’t average. They really only serve to provide a rough and dirty ballpark estimate. We all will fall on one side or the other of the averages, just like a bell curve, and we may find that what these caloric needs and RMR calculators tell us is not anywhere close to what our bodies actually need to maintain itself from day to day. Some of us just have higher metabolisms and some of us have lower metabolisms.
The only way to really know is to get going on your nutrition plan and see what happens! Suppose a formula tells you that with P90X exercise factored in, you need 3000 calories to maintain your weight (like it did for me). The way to know is to eat 3,000 cals per day and do P90X. If my weight goes down, my metabolism must be higher than the formula thought. And vice versa. We all need to play with our own nutrition levels to figure out what our bodies need. After doing P90X and Insanity for a year and a half, I know that to maintain my weight at 215-217, I need about 3100-3200 calories per day. That’s what my 38 year old, 6’4″ body needs.
Now, if I know that about my body, I can tailor my nutrition to meet certain goals. I can use a calorie deficit to lose weight, or a calorie surplus to gain weight. In round 1, I used a 1,000 calorie deficit to lose a lot of body fat and weight. In round 2 and 3, I used a maintenance level of 3000-3200 to keep my body weight the same while building some strength and muscle / losing some body fat. In round 4, I went with a 600 calorie surplus for some mass building.
As you calculate your daily caloric needs, you can use it to maximize your results by dialing in your nutrition as well.
For those of you on a calorie deficit, there are some things you need to consider. First, while doing a rigorous program like P90X or Insanity, you want to be sure you don’t go TOO LOW and slow down your metabolism (this is affectionately known as “starvation mode”).
Is “starvation mode” a reality or a myth? Let’s look at it objectively:
First, what really happens when we eat less than our body expends in a day? Will we lose weight or gain weight? Clearly the answer is that we will LOSE weight. And the opposite is equally true. If we take in more calories than we burn in a day, we will GAIN weight. So if it’s that simple, where does this notion of “starvation mode” come in?
I believe it all comes down to METABOLISM. When we eat less than our body needs to maintain it’s weight, we will lose weight. However, our metabolism will also slow down. And when we eat more than our body needs, our metabolism will speed up. So the change in our metabolism is what is really at play here.
In other words, if we want to lose weight and drop the calories, it will work for a little while, but then our metabolism will slow down a bit, and the weight won’t continue to come off (or at least not like it did initially). To jump start the weight loss, we either need to drop the calories more, or increase our metabolism to break the “plateau” we are in.
I’ve seen research studies showing that when a group of people were put on a calorie-deficit, their metabolism remained at pre-diet levels for about 3-4 weeks, then the metabolism slowed by about 25%. So the dieters who were at a bigger deficit than 25% still lost weight (no “starvation mode”) but that the weight didn’t continue to come off as fast as it did initially. Those who were at a smaller deficit (less than the 25%) found that the metabolism equalled out their calorie deficit and the weight loss stopped altogether.
So, in conclusion, if you run a calorie deficit, will you actually go into “starvation mode” and see your body “hold on to the fat to protect you”? I think the answer is NO! You will still lose body fat if you are taking in less calories than your metabolic daily burn. If not eating enough food led to retained body fat, why are people who are actually malnourished so thin? Because that’s what we would expect! And why are Americans who stuff their face with junk food so fat? Because that makes sense! If “starvation mode” were true, we should see a bunch of skinny Americans because all the junk food we eat should trigger our body to dump fat in response to the excess calories (we could call it “gluttony mode” LOL!). But it doesn’t work that way.
If all this talk about starvation mode really boils down to metabolism and how it changes with our eating patterns, how can we keep the metabolism high (which is what we want), even at a calorie deficit? Or if we have a slow metabolism from years of yo-yo dieting in which we’ve starved our bodies and slowed down our metabolism, what can we do to increase it again?
First, be sure you are exercising! That’s easy if you are on a Beachbody workout program!
Second, eat often. You don’t have to eat a ton of calories. You can still be at a deficit. But your metabolism won’t slow to a crawl if you are refueling your system every 2.5-3 hours.
Third, eat the right kinds of foods. Good long sources of energy are the key, like proteins, good fats, and low glycemic index carbs (aka the “good carbs”). They release energy over a long period of time without the insulin spike that you get from sugars and white foods.
If you are doing those things, you won’t go into “starvation mode” and you’ll continue to see your body fat melt, even at a calorie deficit.
Now don’t get me wrong, there are some calorie totals you don’t want to drop below in order to keep you body functioning properly. These limits are about 900 for women and 1200 for men. But none of us would advocate going that low for weight loss anyways. So we are safely above those levels.
I hope this helps shed some light on how metabolism can work in our favor, and clears up a little about starvation mode, at least from my perspective, based on what I’ve studied. Remember, keep the metabolism up, eat often, eat clean, and eat less than you burn during the day and you WILL lose body fat!
Need a coach?
My email: coachwayne@teamripped.com
IG: @wayne_wyatt
