3.5: What Works?

Diets work in the short-term, simply because we eat less. Keeping those pounds off is another matter. Most fail in the long-run because we go back to eating the way we did before, and our bodies compensate somewhat to taking in fewer calories and weighing less. Also, when we start a diet, we’re motivated and focused, and lose weight. Even the most creative diet plans aren’t all that creative because they use tried-and-true ways to get us to eat less:

Type:	Moderate and general, e.g., Weight Watcher's, American Heart Association Diet
Key features:	Moderate calorie restriction, encourages behavior modification and exercise.
Evaluation:	Slow weight loss; more likely to maintain loss over long-term
Type:	Very low carbohydrate, e.g., Atkins Diet
Key features:	Less than 100 grams carbohydrate/day, restricted food choices
Evaluation:	Ketosis, water loss, faster weight-loss, hard to maintain loss
Type:	Very low fat, e.g., Dean Ornish Diet
Key features:	Mostly vegetarian, high fiber
Evaluation:	Very restricted food choices, hard to stay on diet
Type:	Liquid formula, e.g., SlimFast
Key features:	Formulated products for dieting, low-calorie, nutrient-loaded
Evaluation:	Boring, hard to maintain, low fiber
Type:	Pre-packaged meal plan, e.g., Nutrisystem, Jenny Craig
Key features:	Centers around pre-packaged meals sold as part of plan; behavior
Evaluation:	Expensive; hard to maintain weight loss once off plan
Type:	Novelty diets, e.g., Grapefruit Diet
Key features:	Emphasis on "magical" foods, nutrients, or food combinations
Evaluation:	Tend to be nutritionally poor

Table 3-2: Popular Weight-Loss Diets

• Smaller portions: Another no-brainer. We eat more when there’s more there. Why not the bigger cup of soda if it’s only 25 cents more? “Better” yet, free refills. We eat more from a big bag of chips than from a smaller bag. Bagels, muffins, portions of movie popcorn—have ballooned in size.
• Doesn’t taste as good: Low-fat, low-carb, low-calorie versions don’t taste as good as “real” ice cream, cookies, cheese, chips, candy, and beverages. It’s a no-brainer that when food doesn’t taste as good, we eat less.
• Costs more: Sugar, refined grains, and oil/fat in various combinations give us more calories for our dollar. A diet of snack food and fast food costs less and is more convenient than a diet of whole grains, vegetables, fruit, fish, and lean meat. Low-carb dieters aren’t charged less for leaving the bun off the hamburger. Low-carb foods like steak and lobster are expensive. If a food costs more, we buy—and eat—less of it.
• Keep track: We’re sure to eat fewer chips or cookies if we must write down how many we eat. Most of us can’t eat whatever and whenever we want without putting on weight. When we keep track—whether it’s calories, times we eat, carbs, or portion sizes—we eat less.
• More—or less—convenient: A very convenient plan, such as liquid meals in a can or low-cal frozen meals, works. So does a not-so-convenient plan, such as having to make our own food using special recipes. This plan could even let us eat potato chips whenever we want—we just have to make them ourselves, starting with a raw potato. When you go to your kitchen for an evening snack, what do you find? Cookies, chips, ice cream, frozen pizza, and more? Or is there only fruit, carrot sticks, non-fat yogurt, whole-grain bread, and the like?

Lowdown on Low-Carb

What about the low-carb diets? Yes, we love the shrimp, steaks, and bacon, and may go wild on them at first, but the reality is that we can’t have the pastries or bagels next to the office coffee pot, nor fries with our bunless hamburger. Most or all of what’s in the vending machine is off limits. Dining out, we can’t touch the bread basket, unless we want to eat the butter without the bread. The entrée comes with rice or potatoes or pasta, but we can’t eat that, nor any of the tempting desserts on the menu. We don’t need much math to figure out that this cuts out lots of calories.

It’s ironic that we use low-carb diets to lose weight, because low-carb is a metabolic signal for starvation. It sets in motion a way to prolong life in the continual famines that have beset human history. The usual reason why people aren’t getting any carbohydrate is that there’s no food— they’re starving.

Lunch: 1 tuna sandwich 1 cup milk 2 canned peach halves

755 Calorie Version Tuna sandwich:   2 slices bread (140 cal)   2 oz. tuna packed in oil (110 cal)   1 small dill pickle, chopped (5 cal)   2 Tbs, mayonnaise (200 cal) 1 cup whole milk (150 cal) 2 peach halves canned in heavy syrup (150 cal)

500 Calorie Version Tuna sandwich:   2 slices bread (140 cal)   2 oz. tuna packed in water (75 cal)   1 small dill pickle chopped (5 cal)   2 Tbs. low-fat mayonnaise (100 cal) 1 cup fat-free milk (90 cal) 2 peach halves canned in juice (90 cal)

Table 3-3: Lunch Calories from High vs. Lower Calorie Foods

Our brains need and use glucose relentlessly. When we starve, our body stores of carbohydrate (glycogen) are quickly converted to glucose and depleted. Fat can’t be made into glucose, forcing us to break down body protein to provide the amino acids that can be converted to glucose.

We break down the least essential proteins first, and then move up the hierarchy until we reach the final stage of having to break down the essential protein structures in organs like the heart to provide the brain with glucose.

Our bodies buy time by slowing the process of tearing down body proteins. The low-carb signal triggers the body to increase the production of an alternate fuel for the brain—ketones.

Ketones are normally made in only small amounts from body fat. Muscles and such can burn fat itself for fuel. The brain can’t. Even skinny people have lots of calories stored as fat, so it makes sense for the body to make those calories available to the brain when we’re starving to death. The brain keeps using glucose made from amino acids but, now that more ketones are available, it uses much less.

Those of us on low-carb weight-loss diets certainly aren’t starving to death. What we like about the abundant ketones is that it can cause us to lose our appetite (sometimes to the point of nausea). In addition, some of the ketones overflow into our urine, pulling water along with it. This reduces, by pounds, the amount of water our body retains, buoying our spirits on the bathroom scale.

Some ketones are also lost in our breath. (The ketone lost is acetone, the key ingredient in fingernail-polish remover, giving our breath a fruity odor.) The ketones lost in urine and breath do have some caloric value, but a relatively trivial amount.

Bottom Line

What’s the bottom line on weight-loss diets? The diet that works best is the one that causes you to take in fewer calories. For some, it’s a low-carb diet. For others, it’s a low-fat diet, the paleo diet, intermittent fasting. When calories are controlled for, weight loss from various diets, e.g., low-fat vs. low-carb, are similar.⁹

Of course, the nutritional adequacy of the diet is important. Being more physically active is also an important component, and has many health benefits besides using calories.

We get a lot of health benefits simply by losing excess weight (lower blood pressure, better blood cholesterol levels, less risk of diabetes and heart disease and some cancers, more endurance, less strain on our joints—the list goes on). This, in fact, makes it hard to compare the relative risks and benefits of various diets.

In the short term, anyway, beneficial effects of the weight loss itself can override any effects of the specific dietary components (low carb, low fat, etc.). When studies compare diets where short-term weight loss is greater in one of them, better blood-cholesterol levels, for example, could very well be from the greater weight loss rather than the diet itself.

Whatever method we use to eat fewer calories and use more calories in physical activity, we want one that’s healthful and that we can stick with for the rest of our lives—a permanent change to a healthy diet and lifestyle.