You decide to lose a couple of kilos before the end of the year. Your friend suggests some ideas that worked for him. You change your diet drastically, begin to lose weight and feel great. You reward yourself with small indulgences here and there. Your brain is in overdrive at work; your tiredly firing neurons demand a snack. You slip back into your old eating routine, prepared to load back the kilos that you lost.
But something unexpected happens. This time, when you revert to your greasy eating habits, you put on more weight than you had before! What happened? You just entered the circular world of yo-yo dieting.
The first mistake that you made on your diet was that you slept hungry a few too many times. The stomach may growl, but the brain has a bite. When the glucose-guzzling brain is hungry, all sources of energy — fats, sugars and protein — are game to be consumed. You would hope the isles of fat around the tummy would be the first to go. Unfortunately, all energy stores are not the same and your brain grabs its fix elsewhere.
The first energy source the brain hits is glycogen, the body’s candy store. Glycogen lives in muscles and can break down to release glucose if the body demands. When muscle loses its glycogen, it becomes weak and tired. Part of the reason why endurance athletes load up on carbohydrates before a race is to build up their glycogen stores.
When glycogen stores are used up, the body turns to fats and proteins for energy. Unlike how glycogen can store glucose and fat cells can store fat, the body has no storage cells for protein. When the body turns to protein for fuel, it rips it out of muscles. The good news is that muscle is heavy, so you begin to lose weight. The bad news is that is not the weight you want to lose.
The second mistake you made on your diet was that you did not eat enough protein or continue regular exercise to protect your muscles from being broken down.
To summarise so far, you starved a little too often and lost some weight. Problem was that the weight you lost came from your hard-earned muscles. When your diet starts to slip away and you overeat again, you now replace this muscle with fat. Here is how. When you began your diet, you reduced the total and unspent calories that your body had to store. You lived with a net caloric debt. Challenged by the low caloric environment, your body adapted to become less demanding. Its metabolism slowed and needs for energy decreased. The same body that needed 2,500 kcal a day could do fine with less.
When you regress to poor eating habits, your metabolically slowed body sees a caloric surplus. Even at the normal food levels of before, you now begin to put on weight. And unfortunately these calories do not go to replenish the muscle you lost on the way down. You put on fat. The yo-yo diet has you trade in your toned muscle for some flabby fat.
It gets worse.
If you lost 10 kg on your crash diet, some of those kilos came from muscles. When you put back the kilos, in return you only add fat. Also, 10 kg of fat may weigh the same as 10 kg of muscle, but fat takes up three times as much space as muscle. Your waistline knows what I am talking about.
There is a simple way to escape from a yo-yo diet. Lose weight gradually so you do not put your body through periods of extreme hunger. Include exercise in whatever diet you choose. That will help you keep on muscle and keep off the fat when you grow bored of always being hungry.
Oh, and try to avoid a fad diet like ‘one good meal’ or the ‘fruit juice diet.’ They just don’t work. The women in the room may agree with something I heard from a reliable source. A fad diet is like dating a bad boy — even in the middle of it you know it isn’t going to work!
(This story appears in the 04 December, 2009 issue of Forbes India. You can buy our tablet version from Magzter.com. To visit our Archives, click here.)