Wednesday, 2 January 2013

Motivating Amy Part 3

Part 1
Part 2
(which will also explain why these posts are called 'Motivating Amy'!)

This is one of my favourite subjects, because I like lifting weights. But even if you don't want to go to a gym and fight for space in the free weight area, maintaining and/or building muscle is important, especially when you're dieting.

Here's some maths for you:

A 60kg, 5ft 6 woman uses roughly 1345 calories a day just to survive - heart, lung, kidney, brain etc functions - the important stuff!
Add in a 'light' level of activity - commuting, working in an office, working out a couple of times a week - and this daily requirement increases to 1880 calories.
(Here's the calculator I used but a search of 'calorie requirements' will bring up many others)

So far, so good. I'll assume this woman - I'll call her Amy - is eating 1880 calories because her weight is stable - her calorie intake is matching her calorie output. But she would like to lose weight, and reads about a fad diet  in a magazine which claims 1000 calories a day, plus some strange moves with a couple of cans of baked beans, will help her lose a dress size.

This calorie count is 345 calories less than she needs to survive. Initially her body will rely on body fat and muscle for fuel, but after a couple of weeks (maybe less, maybe more, it depends on the individual) her body will realise it's being starved and cling on to the body fat. Muscle, however, will still be used - it's a rich source of fuel but it also needs fuel to exist, fuel that's very much in short supply. Also, as muscles uses energy for its own purposes it makes sense for the body to get rid of it.

After a few more weeks, Amy's body will have got used to living on 1000 calories (including being a bit more careful how it uses her heart, lungs and other vital organs) and because she is no longer in calorie deficit (ie. her intake is matching her output again) her weight plateaus. Now, either Amy will cut down more calories, or she'll give up the diet because a) it's not working and b) she's hungry and wants to eat proper food again.

Cutting down more will repeat the process I outlined above, but with increasingly serious consequences, so I'll focus on giving up the diet. Amy returns to eating 1880 calories a day, but - BUT! - her body thinks she's overeating by 880 calories because it's been used to living on 1000 calories, and her muscle has been stripped. It takes 3500 extra calories to put on one pound of body fat - which will be about four days!

I hope this makes sense, because it is the reason why NO DIET WILL EVER WORK. Moderation with food and exercise is the best way. If Amy had been maintaining her muscle mass the excess would not have been so extreme when she came off the diet.

Stay tuned for Part 4, when I'll be explaining how to build muscle when you don't
lift weights, or want to lift weights, or have weights to lift!


  1. So interesting - and it backs up what I keep on telling everyone (*smug face*).