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Will I slow my metabolism by eating less?

I always worry that if I eat a lot less calories, my metabolism will adapt and I will be stuck having to eat less and less to lose. Ultimately I would love to be able to lose fat at a higher calorie level – but I also feel that my age and thyroid issue probably makes that a little more difficult.

This is a common concern I hear from readers and my clients. As I bring up eating less to get weight loss started, they often voice their concern over not eating enough.


If that includes you, let me help you put those fears to rest, your metabolism does NOT slow down with losing weight to any degree even remotely close to what the media or some “experts” report. There is a very mild reduction in total calorie expenditure with calorie restriction but it is predominantly from reduced activity, not a lowered basal metabolism. People on low calorie diets move less! We think twice before walking to the far bathroom or using the stairs. etc.

This reduction in non exercise activity thermogenesis (aka NEAT) has been shown to cause a 300-700 calorie drop in the amount of calories a person burns a day. So…. if you want to lose weight without needing much fewer calories, the answer is to keep moving even as you lose weight. Furthermore, having a moderate calorie deficit as opposed to a severe one, makes it easy to keep moving during the day and not become more sedentary. (When you go to 1200 calories a day, it’s like pulling teeth to get off the couch or out of your chair for anything short of a fire in the building).

Moderate calorie deficits are exactly what you get when you form good habits, such as not eating unless you’re hungry, and choosing higher quality foods.

The small change that does happen to basal metabolism (the amount you burn at rest) is largely linked to a decrease in thyroid hormones, and that only becomes significant after bodyfat levels have dipped below a healthy range, as in women with anorexia nervosa. Until you become dangerously thin, your basal metabolism stays relatively unchanged. So if you have any excess fat, you have nothing to worry about.

By eating only when hungry, (and staying active) you’re not going to lose muscle or metabolism, you’re going to lose fat.

(Worrying about slowing your metabolism is a belief that actually keeps people from succeeding with weight loss, and keeps them heavy.) Don’t let this myth scare you out of weight loss success.

Coach Georgie


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  • Tim June 28, 2015, 11:19 pm

    It’s important to note that your BMR is linked to your height, weight, and age, so as you lose weight your metabolism will slow. Not because of eating less, but because your body has less mass to support.

  • Emm November 20, 2014, 6:40 am

    Thank you so incredibly much for this. I’ve been paranoid about slowing down my metabolism throughout my weight loss journey and this was exactly what I needed.

  • Morelli March 3, 2014, 2:34 pm

    Esther, in my experience, losing muscle is not a concern if you’re strength training regularly.
    However, at a certain point, I found I wasn’t getting stronger anymore; workouts weren’t fun anymore. I started eating just a bit more and putting on a little weight to move beyond the lean place I occupied for over 2 years. Ultimately, I want to keep getting stronger, and that means gaining at some point. I find it’s a natural progression that happens over time: you get to your goal and then you need another one!

  • Esther February 26, 2014, 1:57 am

    Wow that was really interesting. Great to get some tangible facts. I think its true that a little bit of information (i.e. a hazy idea that we heard somewhere that eating less slows your metabolism) without knowing exactly what the bottom line is does indeed stall progress and prevent making real changes to get results.
    So, I get now that basal metabolism doesn’t change much until actual body fat levels drop quite low, but I’m still not clear and would really like to know more about what the bottom line is about losing muscle instead of fat in connection with calorie reduction.
    Great article Georgie