I was talking with my mates at lunch about something we’d talked about a lot before, and about which there are a lot of confused opinions on the Internet. The topic was fat, and muscle, and weight loss, and calories. In other words, we were talking about a lot of different things, and I realised after a while that a lot of different propositions were being conflated and meanings were shifting in a way that the premises offered did not support conclusions found, but I’m not best at dealing with conversations in which this is happening at the best of times. I’m a philosopher and I tend to spot quite quickly when this is going on, but I’m not very good at verbally articulating to non-philosophers where the argument has gone astray. Part of it’s a vocab gap - when you’re trained to analyse arguments you’re given tools which very quickly explain to other philosophers where smething has gone awry in a way they can instantly see themselves - part of it’s just that there are a lot of steps to go through and that’s hard to explain in conversation - I can rarely hold the conversation long enough to get out a complete explanation. And then I get frustrated and give up, or I try to short-cut the steps in a way other people can’t follow.
So, this is me trying to work it out longhand. Here’s the rough argument that seemed to be agreed at the end of the discussion:
- Muscle is not really that much more dense than fat
- Even body builders can only put on about 8lbs of muscle a year
- So, the average person trying to get fit won’t put on that much muscle a year
- And my percentage of body fat is not likely to be that different even if I’ve been working out for a year and can see and feel that I am more muscular
- So, even if you have put on muscle you should not make allowances for this in calculating how many calories to eat per day if you’re trying to lose weight
3 and 4 are meant to follow from 1 and 2, and 5 is meant to follow from 1-4. When we look at these premises, though, there’s a great deal of ambiguity. I don’t have the energy to fact check at the moment, so let’s assume for sake of argument that 1 and 2 are true. What constitutes ‘not really that much more dense’ is very vague. It was narrowed down to (I think) 1.15 grams of muscle being equal to 0.9 grams of fat. From which it was then argued that a body builder putting on 8lbs would only weigh 2lbs less than if he had put on 8 lbs of fat, thus not making a great difference to percentage of body fat or what should be considered when calculating calories.
This is a bit confused. Firstly: it is vague as to what it means for a body builder to put on 8lbs of muscle. Is this 8lbs in addition to their weight at the start of that year? How much of their weight constituted fat at the start of the year? If a body builder lost 8lbs of fat but gained 16lbs of muscle, would we still say he had only put on 8lbs of muscle, given that he would only be 8lbs up? Fat loss and muscle-building is by no means as straight forward as any assertiong about putting on xlbs of muscle makes it sound. Sometimes muscle is burned instead of fat in building more muscle. Body builders tend to fluctuate in weight and fat percentage more than ordinary people as they consume high calories in the muscle building phase and then reduce calories and their workouts in the run up to competitions so that the percentage of body fat drops and muscle is more visible through he skin. Comparing an ordinary person trying to tone up and lose weight to a body builder is fraught with problems.
Secondly: even if I lose no weight at all, but convert 8lbs of fat to 8lbs of muscle, I have dramatically reduced the amount of fat in my body. If we accept that I have only increased my body density by 0.25 on those 8lbs I am still a LOT healthier and will have considerably less fat that I need to lose in order to further improve my health. I may not be any thinner at the end of that year, but I can expect it to be easier to become thinner going forward as I do have less fat that I need to lose.
Thirdly: perhaps more significant than muscle density, maintainance of muscles consumes more calories. The muscle itself takes more calories to maintain, but also your overall matabolism is increased, and this is what really affects weight-loss because you burn more calories at rest if you have a higher metabolism. The exercise itself may even damage your fat to muscle ratio if you don’t consume calories afterwards as your body will break down your muscles before it breaks down your fat unless you give it easier calories (in the form of food). I don’t fully understand teh science behind that, but a lot of websites seem to agree on it. Given this (and this is what my doctor says, too) it must be the case that the real benefit of exercise is in raising your at rest metabolism to consume more calories.
What follows directly from this is that having more muscle means that you use more calories just going about your daily business, so if you have more muscle mass you don’t need to cut down as much to lose fat. Given that the body-builder fact fails to show that a person whose weight hasn’t changed much won’t have put on muscle and have a lower percentage of body fat, the conclusion that a year’s worth of exercise will not affect the amount of calories you should consume in order to lose weight is false.