Will NOT Eating the Calories I Burn w/Exercise Mess Up My Metabolism?

dbrady16 · August 2019

My goal is to lose 140 to 150lbs. I've been losing 2.4 pounds very consistently by sticking close to the calorie count suggested by MFP. I'm going to start incorporating exercise into my daily plan (We purchased an elliptical) so I'm wondering if it's okay to NOT increase my calorie intake because of exercise. I've read conflicting articles regarding whether or not this would mess up my metabolism and at age 55 I really can't afford to make it any slower than it already is. So, should I add a portion of the calories burned to my calorie intake or keep my intake at the 1400 calories suggested. Which would be most likely to mess up my metabolism?

MikePTY · August 2019

It's not about messing up your metabolism. But when you work out, your body burns more energy, so you need more calories to properly fuel your body. Otherwise you can get fatigued, and lose weight too rapidly.

Because you have a lot to lose, the truth is that if you incorporate moderate exercise for now, even if you didn't eat the calories back, your body would be able to handle the weight loss for now, because you have high fat stores for it to burn. But as you get closer to your goal, that won't become as sustainable, and could lead to your body burning more muscle in addition to other negative side effects if your calorie deficit is to high. For that reason, I think it's probably better to build the good habit now, and get in the routine of eating your exercise calories back.

If you are worried that the calorie burns are over-exaggerated, you can start by eating 50% of the estimated calories back and see how that works for you. But I would recommend eating something.

AnnPT77 · August 2019

You are already losing weight quite fast. (One percent of current body weight per week is often suggested as a maximum for anyone who's not under close medical supervision for nutritional adequacy and health complications; but lower fractions can be more suitable when within 50 pounds or so of goal weight, or other circumstances make fast loss more risky. You don't say how tall you are, or whether you're male or female, so it's hard to guess what a sensible goal weight might be, or to guess what weight you are now with 140-150 to lose.)

If you add exercise, and keep calories the same, you may lose even faster (unless fatigue saps calories out of your daily life).

IMO, at age 55, it's also hard to afford losing more than the minimum of lean tissue while losing fat. Muscle, in particular, is slower and more difficult to regain as we age (not impossible); and the physical stress of rapid weight loss may be more likely to bring on its own health problems, which are slower to recover from when we're older. (BTW, I'm now 63, and lost from obese to a healthy weight at age 59-60, so talking about potential effects with aging is not theoretical on my part: I lost too fast for a short time, and it took weeks to recover normal strength and energy level.)

Striking a balance is important: Getting out of a seriously overweight situation as rapidly as practical, while minimizing potential health risks associated with fast loss.

For those reasons, I'd suggest starting your new routine by eating back a significant fraction of your exercise calories, striving to keep your loss rate reasonable for your current body size. The new exercise itself will create physical stress on your body, especially at first; letting that exercise create a super-fast loss rate increases the risk. If you ramp up your exercise gradually, are losing at a sensible rate, and reach a point where the exercise is well-integrated into your daily routine, then you can talk with your doctor about whether it's safe and reasonable for you to be losing even faster.

Just my opinion, obviously.

shaumom · August 2019

I think it can help to look at it in a different way.

The calculations for how many calories you should eat are based on how many calories you burn daily, as a general rule. Your maintenance level of calorie burn, you know?

Because while it IS individual how much you burn daily, it can be averaged fairly well for most people as long as your weight and general daily activity level is known (sedentary, active, etc...). But it is simply made up of all the different calorie usages during the day.

X calories used to make heart beat for a day.
Y calories used to digest food for a day.
Z calories used to move your body around for a day (differs depending on activity level and weight).

'Exercise calories' is literally just a name we have given for additions to the 'calories used to move your body around' category. Mostly because if we are exercising, it's often not the same amount every day (otherwise, we could just change the activity level on our initial calculations and be done with it).

So it may help to remember that exercise calories are not some type of, hmmm, extra or special type calorie in the calculations, I guess I would say. You have a daily amount of calories burned, and that's really it. HOWEVER those calories were burned, it's still just one category.

So if you are looking at how much weight you are losing, and using calories to figure that out, the net loss of calories is really all that should be looked at to judge how it is going to affect you rather than trying to separate out your burned calories into differently judged sections. Now whether a higher or lower calorie net loss is better? The guys above have more information on that, IMO. I'm just mentioning this because I think it can be helpful to remember, when trying to work out how much to exercise or eat.

cmriverside · August 2019

What MikePTY said. Every word of it ^^

Will NOT Eating the Calories I Burn w/Exercise Mess Up My Metabolism?

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