Why One Diet Doesn’t Work for Everybody: Weight Loss Individualization

One of the mysteries at the heart of modern obesity research is that two different people can follow the same weight loss diet with entirely different results. One dieter who sticks to a diet plan may lose 50 pounds in three months. Another dieter who sticks to the same diet plan may gain 10 pounds. This is even sometimes true when the two dieters are of the same race, same gender, same socioeconomic class, and same age. High-protein, high-carb, low-fat, high-fat, no diet works for everyone. Why should this be?

Obesity Is Not a Single Disease

Even though some American doctors still consider obesity to be a moral failing, it's really disease, or, more accurately, a collection of diseases. Some studies even claim that obesity is a genetic disease. Two people can have the same amount of excess weight, but they may have put it on for very different reasons. As Dr. Lee Kaplan, director of the obesity, metabolism and nutrition institute at Massachusetts General Hospital and Harvard Medical School says, insisting that there is just one cause and one way to fight obesity (by banning sugary soft drinks, clearing out snack foods from convenience stores, or helping people get more sleep, for example) makes no more sense than using sunscreen to prevent lung cancer.

Some of these 59 types of obesity can be linked to mutations in up to 25 different genes. Having a mutation in just one of these 25 genes is enough to guarantee that you will be obese. Some of these genes interfere with the ability of fat cells to generate the hormone leptin, which tells the brain that they have stored enough excess calories. Some of these these genes interfere with the ability of the brain to make the messenger molecules after it receives leptin that suppress appetite and slow down the storage of excess carbohydrate calories in the liver.

However, it isn't just 25 genes that can cause obesity. There are 300 more genes that can cause a tendency toward some weight gain. A combination of mutations in these genes can add up to overweight or obesity. That's a total of at least 325 ways that you can be destined to gain weight from birth. But there are other factors beyond simple overeating that lead to weight gain.

Certain Medications Can Interfere with Your Weight Loss Diet

Medication is another culprit in weight gain. Insulin helps your cells receive sugar from the bloodstream, but it also keeps them from using fat for fuel. Any medication diabetics take for lowering blood sugar levels typically will also increase weight.

Certain antipsychotic drugs stimulate weight gain. Beta-blockers for high blood pressure slow the heart rate so that it is necessary to consume even fewer calories to lose weight. Steroids to control inflammation interfere with water and weight loss and make it impossible to lose weight fast.

Certain Health Conditions Also Force You to Cut More Calories to Lose Weight

Hypothyroidism causes weight loss battle: it slows down the body's process of burning carbohydrates. Tumors of the hypothalamus interfere with the body's "thermostat" so fewer calories are burned. Any condition that limits mobility (arthritis, for example, or obesity itself) also primes weight gain.

One Weight Loss Diet Really Doesn't Work for Everyone

Since the 1990's, a variety of diets have promoted restriction of certain macronutrients (carbohydrate, protein, or fat) as a tool for quick weight loss. The famous Dr. Barry Sears of Zone Diet fame copied a diet used for feeding race horses to propose weight loss by getting 30 percent of calories from protein foods, 30 percent of calories from fat, and 40 percent of calories from carbohydrates. Dr. Dean Ornish, an ethical vegan, recommended eliminating all foods of animal origin and getting no more than 10 percent of calories from fat. The late Dr. Robert Atkins took the exact opposite approach, lauding fat and protein but insisting that no more than 10 percent of calories should come from carbs.

The truth is, none of these diets works reliably well. Dr. Frank Sacks, a professor of nutrition at Harvard, recruited 811 adults to follow one of four different diet plans, and gave them access to coaches who would help stick to their diet plan. The four diets ranged over the span of what has become popular. Two diets were low in fat. One low-fat diet, however, was high in protein and the other had average amounts of protein. Two others were high in fat. One of those high-fat diets was high-protein while the other was average in protein. Dieters were instructed to record everything they ate and drank, and to exercise at least 90 minutes a week. The diets lasted two years.

How much weight do you suppose dieters, on average, lost by dieting for two whole years? The average weight loss in the each of the four diet groups was just three to four kilograms, or seven to nine pounds. Even though dieters were given plans that reduced their calories by 750 per day, which should have resulted in a loss of a pound (450 grams) every four days, the average weight loss was closer to a pound every four months. The problem wasn't just that dieters were cheating. Every plan had a few participants who lost 20 kilograms (44 pounds) or more, and every plan had at least a few dieters who gained weight.

The truth is, some people will lose weight on a low glycemic-load diet (a diet that not only restrict foods by their glycemic index but also restricts how much of those foods are allowed), and others will gain. Some people will get nearly miraculous results by taking the stimulant phentermine for a year or two, and then start gaining weight even though they are still taking the drug. Some people need to count each and every calorie each and every day. Others lose weight when they vary their intake day by day. Some people lose weight by working out hard, but gain it back when they resume a more moderate exercise program.

The simple fact is, you are very lucky if the first weight loss plan you try works for you. But don't give up. There are countless variations of diet plans. There are at least 15 diet drugs. In extreme cases (and for anyone who has uncontrolled diabetes) there is weight loss surgery. It can take several years to find the program that works for you, but persist in your efforts. Just as no diet works for everyone, some diet will work for you if you keep trying to find it.