I wrote about Basal Metabolic Rate/Metabolism in a previous post. To sum that post up, your body burns through over 90% of its energy just doing the bare basics of keeping you alive (heating, breathing, etc). Only 4-8% is usually contributed to exercise unless you are deciding to exercise 5 hours a day like the Biggest Loser contestants. What contributes significantly to your metabolic rate (or Daily metabolic expenditure) is your food intake. Reduce it by 25% and your metabolism reduces by 25% or more to compensate because it detects less in, so uses less. Hence, why caloric restriction only goes so far and isn’t the solution for long term weight loss, and why concentrating on reducing insulin resistance is the key.
There is a concept that Dr Fung raises in his videos and his blog posts, which a Google search can also find a few posts from others, is “Body Set Weight”. The concept is that your weight is a “thermostat”. It has a “body set weight” which it is set to, so when you try to do things like reduce your calories and you lose weight, say over 6 months, your body goes “hey, this is below my body set weight” and increases hormones like “gherlin” which is your hunger hormone, which tells you that your body needs more food so it can get back to its body set weight. Slowly, but surely, the weight creeps back up back to the “body set weight”.
Do caloric reduction/restriction like the Biggest Losers did and the end result is that your metabolism slows and is lowered for a prolong period of time. In that study, even after 6 years after the Biggest Loser show, the contestants had regained their original weight, and their metabolism was about as low as it was at the end of the show, which was lower than when they started the show! So they regained weight with worse metabolism after 6 years!
You’ve probably experienced the effects of your own “body set weight”. For me, in the past couple years while doing my Nutribullet, it was about the 76-77kg mark, where any period where my weight would drop under 75 kg would be short and unsustainable, and it will eventually get dragged back, surely to the 76-77kg mark. On the flip side, any time that I went over 78kg, it too was short lived and it also went back to the 76-77kg mark.
From the below you can see that having a weight of 76-77kg for my 178cm height is classified on the BMI scale as just on the border of “healthy weight range”, with a mid point about 70kg.
I’m not entirely sure whether weighing 70kg is a “healthy” weight for my height, and definitely sure that 60kg is getting a bit on the ridiculously thin side. BMI has been used for a long time to give a ball park figure of what your weight should be for your height, but does not take into account whether you are a body builder of full muscle and not much fat, or all fat and not much muscle.
So then comes waist measurement around your belly button area. This takes into account the fat around your organs which is a indicator to increased risk factors for a lot of nasty things. Again, I’m not a medical professional, and this is just from what I’ve picked up over the years through my journey of health and wellness. If your waist measurement is below a certain amount, independent of your height, then you are in a “lower risk” category.