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.