In Victorian England where faddish eccentricities abounded, there were few more bizarre than the tapeworm regimen, wherein dieters ingested an unfertilized tapeworm larvae, then fed it back with digestively undigested meals. It goes without saying that the tapeworm diet is one of the most hazardous, not to mention unhealthy, ways of controlling your calorie count. Still, while the modern fad diet is rarely as extreme as this, it does promise something akin; namely, the liberating process of rapid weight loss.
Still, do any ‘fast diets’ actually work? And do any of them actually work for your health? For an answer, let’s return to the thought experiment.
Two equally tall and heavy twins, Sam and Felix, would both like to go on a diet. Before starting the diet, they have the same body weight and identical fat and muscle mass. Sam hopes to go slowly. Felix wants to go fast.
Through each week, Sam plans to reduce the calories he ingests and to increase the exercise that he normally does. With fewer calories ingested, and more exerted, he is forcing his body into an energy deficit. His body responds to this by breaking into his emergency glucose supply, stashed in your liver in carbohydrate form (glycogen). About 4–6 hours later, the body turns to burning fat as a major energy source, releasing the lipid droplets stored within fat cells into the bloodstream where they are broken down into compounds that can provide circulating energy for organs and tissues.
Felix wants his body to create an energy deficit in a similar manner by extreme calorie restriction. While Sam is still chugging along at a rapid-but-sustainable-energy-loss pace, picking himself up from fainting after downing that glass of flat coke by tucking into some more pork and beans, Felix is already eating virtually nothing. Felix’s body is doing its best to save itself by going into a state of starvation. His emergency glucose ran out within 18 hours, whereas Sam is sitting on a huge reserve. And while Sam’s calorie-rich and nourishing healthy meals are slowly topping up his glycogen stores, Felix’s low-calorie intake doesn’t do this. His body is now desperate for energy, and so it breaks down other materials — including his muscles. Meanwhile, Sam’s healthy running habit is retaining his muscle mass so he burns more energy during exercise and at rest, so it is easier for him to lose weight. Felix is burning up muscle mass and fewer calories than he ever had for those basic needs further slowing the rate of loss.
Notwithstanding all of this, there is one aspect of Felix’s fast diet that might convince the dieter that he is on the right track. Each gram of glycogen is coupled with three to four grams of water. Up to two kilograms of water weight come with that, all of which will be lost when the glycogen is depleted. Felix may feel like that is good because of how quickly he is losing weight. But when he stops starving himself, that weight will be regained. His body will repopulate its glycogen store.
Felix’s diet doesn’t actually help — in fact, it’s quite harmful — but extreme calorie-deprivation regimens aren’t the only quick-weight-loss plans that are being marketed today. Diets called ‘detox diets’ either allot or withhold foods that are designed to provide specific nutrients in large quantities. Such plans can sometimes treat obvious nutritional problems, but they’re still far too specific in their prescriptions to serve as general panaceas. For someone who is dangerously low in vitamin A, a juice diet might help. But for someone who is dangerously high in the same vitamin, juicing is a recipe for disaster. And even for a person who is either deficient or oversupplied with some nutrients, juicing to lose weight is likely to compromise the immune system for weeks or even months, a consequence of insufficient essential fats and proteins.
And that’s where all this fast food dieting goes wrong — whether you’re decreasing your calories or food groups, extreme diets are a stress to your body. There are well-documented rates of healthy weight loss fuelled by both diet and exercise that take into account genetic and medical variances, and holding to those timeframes demands a way of eating that is sustainable.
And some of the nastier side effects of extremist diets don’t even warrant discussion, as no one ever actually stays on them, which overlooks the fact that many cultures have neurotic attitudes towards weight, and people pressure each other into dieting for non-health or non-happiness related reasons. So don’t go fast — go slow — in reaching out to understand the healthy lifestyle that will serve you best.