Wednesday, April 21, 2010

The Secret to Weight Loss

This is a "common misconceptions" post that I've been meaning to do for a long time, and thanks to a recent article in The New York Times I finally have a good reason. More on that later.

Everybody knows weight loss is a big deal, the fact is obvious from the astounding range of products/services with weighty promises (lose 30 pounds in 30 days!!!); the advertisements assault us constantly, from every possible angle. Given that the majority of US Americans are considered overweight in a culture with highest regards only for the exact opposite build, it's really no surprise that weight loss is big business. The real surprise is just how successful such ventures are when practically all of them make explicitly outrageous claims and just as many (if not more) are wholly ineffective. The truth is that with few exceptions commercial weight loss products are simply fraudulent--they are designed to take your money, not to help you lose weight.

I know the secret to losing weight, and I'm willing to share it... for free! It is very simple, and not simple in the subtly very complicated way, just simple. Ready?

How to lose weight:  Eat less.

 It's a matter of physics. Imagine an extreme case where a person doesn't eat or drink anything; by the very laws of nature and obvious from elementary intuition, it is impossible for that person to gain weight. This would be just like setting a scale in a sealed room: it would be very silly to think that the scale might at any point suddenly measure any more weight than it has all along. Humans are magnificently, extraordinarily, incomprehensibly complex systems, but that doesn't exempt us from the laws of physics. Unless more stuff is added to a body, that body will either maintain or lose weight. In case it isn't obvious, let me remind you that abstaining from all consumption for longer than a little while is a bad idea--remember, the rule is to eat less, not to eat nothing.

Let's explore the physics in slightly more detail. The main reason we eat is to supply our body with energy; our bodies need fuel to keep the magic alive, just like a car needs gas to move. Clearly it would be a bad setup if the energy we consume couldn't be stored, like a car without a gas tank we wouldn't get very far. There are a variety of ways the human body can store energy, but the presently relevant one is best known as fat. Call me crazy, but next time you see that extra bit of flab, try being grateful--if it weren't for that "unsightly" bit of excess, a few missed meals would result in death. I don't know about you, but I'd rather have a less than optimal social image than be dead.

So fat is stored energy, but what's this energy? Is there any way to quantify it so that its consumption might be regulated? In fact, yes, there is! The energy in food is also known as Calories, which is actually a kilocalorie or 1,000 calories. A calorie is a unit of energy, just like an hour is a unit of time. If you eat 2,000 Calories in a day and only use half of them, the rest will be stored, with some portion of them being stored as fat, it's as simple as that! If you are gaining weight and it's not because you're building muscle mass, you are eating more energy than you're using. Here's the Eureka moment!

How to lose weight (revised): Eat fewer calories than you use.

But wait, what about fatty foods, exercise, and metabolism, don't these play a major role in weight loss? Lets look at each of them.

Fatty Foods
One of the strongest diet related misconceptions around is that eating foods with excess fat, saturated, unsaturated, or otherwise will lead to increased body fat. This isn't true, food fat doesn't automatically turn into body fat. Perhaps this misconception arose because lipid nutrients and adipose tissue are both known colloquially as fat, but the notion that consumed lipids will transform into adipose tissue is as silly as the notion that eating brain will make a person smarter. Anybody can eat pure fat every day and lose weight, because the amount of fat in a food doesn't matter for weight management, what matters is the amount of Calories in the food and how much food (ergo how many Calories) is consumed. It's true that fat, with 9 Calories per gram, has a higher energy density than protein and carbohydrates, which have 4 Calories per gram, but for the purposes of weight loss this is moot--all Calories in a food, regardless of the source, are accounted for by the "Calories" figure on every nutritional label. Predictably there's a fair degree of complexity in how effectively food energy is captured, but the given number of Calories represents the maximum; if you closely regulate energy intake, you will realize there are no magical foods that cause body fat. Often, however, energy intake is far from regulated, far even from monitored, and it is very easy to underestimate how many Calories are eaten in a day. One case deserves special mention: high-fructose corn syrup (HFCS), the modern sweetener du jour, has been shown in a recent Princeton study to lead to more weight gain in mice than equal amounts of cane sugar. The theory I've heard is that HFCS is far more easily digested than cane sugar, and since digestion requires energy, HFCS results in more energy than an equal amount of sugar.

When people think weight loss, they usually think exercise. It's always a point of contention when I say it, but exercise does very little to hasten weight loss. The reason is that the body burns a lot of energy no matter what its doing; for most people exercise causes only a marginal increase in energy consumption from the already high baseline. Remember the NYTimes article I mentioned? Here's a quote from it:
“In general, exercise by itself is pretty useless for weight loss,” says Eric Ravussin, a professor at the Pennington Biomedical Research Center in Baton Rouge, La., and an expert on weight loss.
The exception here is athletes, whom require many more calories than everybody else. This is because athletes have bodies that are especially efficient in utilizing energy--in other words, they have a higher basal metabolic rate. For those of us who aren't professionally physically fit, the connection between exercise and weight loss isn't anywhere near as clear cut. For more information on this topic I recommend reading the aforementioned NYTimes article: "Weighing the Evidence on Exercise." Beyond weight loss, keep in mind that frequent aerobic exercise is universally acknowledged as a critical component in the maintenance of cardiovascular health.

One of my pet-peeves, if you can call it that, is when people disseminate false information. We live in an age when almost the full knowledge of Earth is accessible on demand, so the reasoning goes that it's time we stop defaulting to wild speculation and just google it. Of course I have nothing wrong with wild speculation, my displeasure arises when the speculation is presented as fact. I'm bringing this up because it's relevant to the topic at hand, metabolism. Everybody has heard the word, it's used all the time, especially in regard to weight management, but what does it mean? What is metabolism? For all the mention it gets, I'd think everyone would be familiar with what exactly was being referred to. If you visit the Wikipedia page for metabolism, you might find that the subject is rather complicated; the summary refers to cellular respiration, metabolic pathways, and the carboxylic acids that are part of the citric acid cycle. That doesn't sound like weight loss! Metabolism is something of a shotgun term that refers to the chemistry of life. The basal metabolic rate is a bit more specific, as it refers to the amount of energy an organism expends while at rest and in a post-absorptive state. Since basal metabolic rate is roughly energy expenditure, it must be able to indicate how many Calories are needed to manage weight, and indeed it does. Interestingly enough, metabolic rate is strongly correlated with lean muscle mass and the same figure has been arrived at for all people: 16 Calories per pound of lean mass per day. This means an estimate for how many Calories you need each day can be found by multiplying your lean mass by 16. This also indicates what has been shown in other studies as well: the best known way to increase the basal metabolic rate is by increasing lean muscle mass.

Just one final note: losing more than a pound or two a week is neither healthy nor permanent.

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