4 Weight-Loss Myths
Believe the myths, and despair?
June 15, 2013 - 11:30 am
The hypothesis: a slow carb diet with intermittent fasting, along with continuing to work for greater integration of exercise into my daily life, will help me lose weight and improve my still-too-high blood sugar. This is the third experiment of a 13 weeks duration, in an ongoing series. Follow my daily updates at Facebook and join me on Fitocracy to follow my progress there, of which there will be some. Honest.
13 Weeks: Season 3, Week 3
I’ve been personally interested in weight loss and associated things pretty much my entire life. Long-time readers will remember me mentioning being insulted about my weight — told I was repulsive, in fact — when I was seven or eight. I first started actively dieting, hoping to lose weight and not be repulsive, when I was about 12, and immediately ran into trouble with it. After a certain length of time, even strictly following a 1200 kcal a day diet, I’d stop losing weight.
Since this was well-known to be impossible, it must have been that I was cheating on the diet. I knew I wasn’t, but who’s going to believe a 12 year old?
Fast forward to when I was working on my PhD at Duke Medical School. By this time I was considerably more sophisticated — well, except emotionally, I still felt basically that I was repulsive — and I had started reading seriously about weight regulation. I discovered that a whole lot of things I’d been told were absolutely certain, weren’t. Many of those things are still generally believed, and I think they keep people from doing what is useful, get them to do a lot of things that aren’t particularly useful, and frankly cause many people to despair.
Myth #1: The “Ideal” Weight Is Healthiest.
This one has made recent news. Our idea of what is an ideal weight comes originally from studies done by life insurance companies. The insurance company actuaries spend their time trying to decide how much to charge for an insurance policy, which is essentially a bet: you are betting the insurance company that you will die young, and the insurance company bets you will live to a ripe old age. (I’ve explained the basic math of insurance on PJM before.) So insurance companies, primarily MetLife, did studies in the ’50s and computed ideal weights from them.
These studies were very empirical, and they really were aimed entirely at determining how much to charge middle-aged white people for insurance. They did a good job of that, but they didn’t account for any number of confounding factors. However, once they had published the tables, these tables went from being essentially descriptive — “middle aged people seem to live longest in these height/weight ratios” — to be taken as prescriptive — “everyone’s ideal weight is given by these tables of height/weight ratio.” Now we define these “ideal weights” in terms of body-mass index, BMI, which sounds much more precise and scientific, but turns out to be simply a height/weight ratio.
Pretty much anyone can see that BMI is questionable — for example, a champion bodybuilder with a competition body fat of 3 percent may well have a “very obese” BMI. (On the other hand, it’s unclear that very low body fat is necessarily healthy either — in fact, we know it’s certainly not healthy for women.)
The problem is that epidemiology, the study of health and disease across large populations, keeps finding results that don’t quite fit this idea of ideal weight. Most recently, a study by Katherine Flegel and others published in January of this year showed that the notion of ideal weight was massively oversimplified. The study found two things: first, that for younger people, BMI doesn’t have any strong effects, and as you get older, the BMI associated with the least likelihood of dying increases.
In other words, if you don’t want to die the data suggests you actually want a slightly higher BMI as you get older.
What’s more, other studies say that BMI isn’t as good a predictor as simply the length of your belt — the larger your waistline, the more likely you were to have a whole lot of different health problems like type-2 diabetes. (This one does fit the bodybuilder example, too — bodybuilders do generally have small waists.)
Now, this can be taken too far — there’s no doubt that real obesity has bad effects on your health. (My knees would tell you that, if asked. And if knees could talk.) But the truth is that being a little overweight is either not harmful or may actually be helpful.
Myth #2: Your Weight Depends Only On Calories-In Versus Calories-Out.
This one has also come up here before. My own data, collected over more than six months and my first two 13-weeks experiments, has shown that it certainly doesn’t hold for me. Over the first about 10 weeks of my very low-carb diet, I lost weight much more rapidly than could be accounted for by a calorie deficit; since then as I crossed the Great Plateau, my weight loss has been considerably less than calorie deficit should predict.
Again, this is hardly unknown scientifically, going back to very careful studies of Pima Indians. In those studies, the subject literally lives in a big closed environment, and their food consumption and calorie output can be precisely measured. What they found was that in fact the body adapts to starvation; if you stay on a low calorie diet, your body will slow down to save calories.
Here’s how it works: your body needs a certain amount of energy every day, simply to keep your heart beating and your nerves nerving. That bare minimum is called the basal metabolic rate. What the Pima Indian studies showed was that when they kept to a low-calorie diet, their basal matabolic rate actually slowed down to try to match.
They saw what I’d seen in myself when I was 12, and am probably seeing now — their bodies could down-regulate to handle the lower calorie intake.
Evolutionarily, of course, our bodies don’t necessarily want to lose weight anyway — a fat person can still breed, and someone with a little extra fat is more likely to survive when the mastodon harvest is a little slim.
As with the BMI, this doesn’t mean that dieting is completely pointless — if you reduce calories enough you will lose weight. And eventually die. But it means that the well-meaning people who say “Oh, losing weight is simple — cut down what you eat and you’ll lose weight; if you’re not losing weight, you must not really be cutting back” are wrong.
Myth # 3: What You Eat Doesn’t Matter.
Myth #4: Fat in Your Diet Is The Only Thing That Matters.
Once again, the actual science doesn’t actually support this. We’ve talked before about the research Gary Taubes surveyed in Good Calories, Bad Calories and Why We Get Fat. Basically, there is a lot of evidence that for a large population, the people who have what’s called “metabolic syndrome” or “syndrome X,” the amount of easily available carbohydrates in their diets has a big influence on their weight, and on the progress of their metabolic syndrome into frank type-2 diabetes.
That population is relatively easy to identify — they tend (callback to myth 1) to have big waistlines, to put weight on near their bellybutton instead of on their … hips. Take those people off carbs, and many of them lose weight even at roughly the same caloric intake. Other indicators of general health, like blood pressure, average blood sugar, and fats in the blood — the “lipid profile” which includes total cholesterol, triglycerides, and the various lipid fractions — all improve, usually markedly.
Public nutrition authorities, however, have for various reasons been pushing a different idea, that it’s the amont of fat in your diet that really matters, and a grain-based diet is the healthiest.
Again, the science doesn’t seem to stand up very well. There has been some evidence that a very low fat diet can improve cardiac health in people with pre-existing cardiac disease. Dr. Dean Ornish is the most vocal proponent of this idea.
The thing is that there’s relatively little evidence that this is really a healthy diet for people in general, and having tried the Ornish diet myself, I can tell you that it really has some issues just in terms of compliance. There are only so many bowls of salad and unbuttered brown rice you can eat. What’s more, because these diets are extremely low in fat, they force you to be nearly vegan, and for most people this also means it’s hard to eat enough calories. You’ll certainly lose weight on an Ornish diet, but most people are hungry all the time.
But now consider what happens when people adopt these dietary recommendations. You naturally go toward eating more grains, which means eating more easily available carbs.
In other words, it’s very likely that at least for those people who have metabolic syndrome, the low-fat grain-intensive recommendations are actively harmful.
This isn’t scientifically certain, and in fact is rather controversial, but there is one very interesting point to note: the increasing “obesity crisis” correlated very well with the introduction of the low-fat, high-grain dietary recommendations.
What To Make of This?
Well, so now we’re certainly in a pickle, aren’t we? (Pickles do appear to be good for you, by the way.) But if low-calorie diets don’t work as advertised, and low-fat eating doesn’t work, how about going the other direction?
Well, my own experience is both good and bad. For my first 26 weeks, I’ve followed a high-fat, high-protein, low-carb diet, and a lot of the effects were good: I have lost weight, my blood sugar is much better, and my lipid profile is very good. Which is a big surprise when you realize that I’m eating what would be considered about the worst possible diet in that respect.
But after 26 weeks, I’ve stopped losing weight, dammit. It’s very hard to explain — my food diary shows I’m still at what should be a significant calorie deficit, I was very successful at cutting carbs, and hell, my blood sugar was down so far I was having hypoglycemic episodes. But my weight stuck at very close to 273 pounds, about 50 pounds more than I would like.
Okay, Charlie’s First Law of Change is that the only thing that can’t help is to not do anything different, so I’ve changed my diet, adding a little more carbs in the form of beans, and at the same time taking one or two days a week of near-fasting, targeting about 600 kcals a day.
This may be doing some good although it’s a little too early to tell — right now I’m losing weight at a rate of about a pound and a half a week. (The variance is smaller too, but it’s still around two pounds, so it’s really too early to say that there is any real effect.) On the other hand my blood sugar seems to be straightening out a little — I’m not having the real low lows.
I think the real key, though, is that the biggest myth is the idea that we really understand the whole problem of weight regulation. Pick any diet, and you’ll find people who have great success, and people who don’t.
Paying attention to the myths, though, when a diet doesn’t have the desired effects, we tend to blame ourselves. Better to remember that no one really understands this well yet; if we try something, and it doesn’t work, it doesn’t mean we failed — it just means we’re not part of the group for whom that one notion worked. Give an approach a fair trial. Then if it fails, try something else.