Summary: Want to Lose Weight? What You Need to Know about Eating and Exercise

Dr. Roberts wrote a feature article for the magazine Scientific American that discusses key learnings from her research. We know you’re busy (and the article is subscriber-only) so here are some useful highlights from the article. By the way, if you’re a subscriber, you can see it here:

Scientific American: Want to Lose Weight? What You Need to Know about Eating and Exercise

Key learnings:

What you eat is more important than how much you exercise. Exercise is not the most important thing to focus on when you want to lose weight — although it has numerous other health benefits, including maintaining a healthy weight. As Dr. Roberts’ lab has proved, what you eat and how much you eat play a substantially greater role in determining whether you shed kilograms. But her research has gone much deeper, showing that different people lose weight more effectively with different foods. This realization allows us to create personalized weight-loss plans for individuals that work better than any one-size-fits-all advice.

Food composition matters. A food’s physical properties and composition play a greater role in how completely the body can digest and absorb calories than investigators had anticipated. For example, raw whole almonds provide about a third fewer calories compared to an equivalent mass of almond butter.

Likewise, whole grains, oats and high-fiber cereals are also digested less efficiently than nutritionists used to think. A recent study in Dr. Roberts’ lab looked at what happened when volunteers consumed a whole-grain diet that included 30 grams of dietary fiber versus more typical American fare that contained half as much fiber. They detected an increase in the number of calories excreted in the stool, as well as a bump in metabolism. Together these changes amounted to a net benefit of nearly 100 calories a day — which can have a substantial effect on weight over a period of years. This and other studies have proven that not all calories are always equal. And that a cleverly designed meal plan can increase satiety and reduce absorbed calories — without discomfort.

Obesity increases the risk of all the major noncommunicable diseases, including type 2 diabetes, heart disease, stroke and several types of cancers — enough to decrease a person’s potential life span by as much as 14 years. Research shows that excessive weight also interferes with our body’s ability to fight off infections, sleep deeply, and age well, among other problems. Therefore, maintaining a healthy weight is a key ingredient in healthy aging.

The challenge of weight is too often reduced to a simple mathematical formula: burn more calories than you consume. For decades health experts figured that it did not matter too much how you created that deficit — that you could lose weight with any combination of increased exercise and reduced consumption of food. But this assumption does not take into account the complexities of human physiology and psychology, and so it quickly falls apart when tested against real-world experience, as shown in Dr. Roberts’ laboratory research. Simplistic plans can fail in the face of human complexity.

Humans, like other primates, do not need a lot of calories to stay healthy and active. Other species require two to three times more calories, kilogram per kilogram, than primates to maintain their weight. We are — somewhat unfortunately — extremely efficient, with an ability to adjust our metabolism to match environmental demands. It is tempting to assume that Americans have low calorie requirements because we lead sedentary lives, but researchers have compared our calorie needs to indigenous populations leading very active lives and found them roughly equivalent. It appears the more demands you place on your body, the more efficient it becomes.

500 Calories: Government data show that, on average, Americans consume 500 more calories each day than they did in the 1970s. Is it any wonder, then, that so many of us have become overweight or obese in an obesogenic environment? If current trends continue, health experts predict that half of all Americans will be obese by 2030. And the weight problem is much too complex to be solved with quick fixes or fads.

Metabolism and Activity

It’s a question of balance — in and out. Physical activity certainly helps to keep your heart, brain, bones, and other body parts in good working order. But detailed measurements conducted in Dr. Roberts’ lab (and others) show that physical activity is responsible for only about one third of total energy expenditure. The body’s basal metabolism — the energy it needs to maintain itself at rest — makes up the other two thirds.

Brain vs Muscle. Intriguingly, the areas of the body with the greatest energy requirement are the brain and certain internal organs, such as the heart and kidneys — not the skeletal muscle. Although strength training can boost basal metabolism modestly.

It takes energy to digest food. And it “costs” about twice as much energy to digest protein vs carbs. But regardless, the amount of energy “lost” to digesting our food generally only represents a single-digit fraction of the total calories in the meal. But the less processed that meal, the better, because super-processed foods digest more easily and raise blood sugar faster — two things to avoid.

Metabolism varies between people, and over time. Two people of the same age, gender and size, can have a basal metabolism that varies as much as 500 calories a day, even within families. And metabolism drops by as much as 800 calories a day between age 22 and 72. So you can’t eat like you’re in college when you’re retired.

We evolved to hold onto calories. The human body is subject to the pressures of evolution, which would have favored those who could hold on to their energy stores by becoming even more fuel-efficient under stress or during times of famine. And indeed, studies show that metabolic rate drops somewhat during active weight loss. Once a person’s weight has stabilized at a new, lower level, exercise can help in weight management by compensating for the reduced energy requirement of a hard-won smaller body — as well as eating amounts appropriate to your smaller size, and current age.

Tricking your brain, solving hunger

Your hungry brain. Hunger has a valuable role — it is on a hair trigger to keep us alive. Unfortunately most people do not need this “feature” anymore, because we are drowning in food, not fighting famine. But the brain’s systems are hardwired, so there is no point in fighting your brain directly. Instead, one of the keys to successful weight management is to prevent hunger and temptation from happening in the first place.

Slow vs fast food. A low-glycemic meal sets you up to eat less at your next meal. Feeding tests by several labs, including Dr. Roberts’ lab, show that meals higher in protein or fiber (those that do not cause a sudden spike in blood sugar) are generally more satisfying and better at suppressing hunger. Dr. Roberts published a summary in 2000 indicating that free-choice calorie consumption in the hours following a breakfast with a high glycemic index was 29 percent greater than after a morning meal with a low glycemic index. Imagine never needing to snack again.

It is possible to reduce hunger during weight loss by choosing the right foods. When Dr. Roberts randomly assigned subjects to either her weight-loss program of foods high in protein and fiber and low in glycemic index (fish, beans, apples, vegetables, grilled chicken and wheat berries, for example) or to a “waiting list,” over six months the members of the experimental group reported hunger levels that decreased to below the values measured before the program began. That means they ate less and had less hunger on fewer calories than when they were eating “normally”. And weight dropped too. By the end of the study, the experimental group had lost an average of eight kilograms (that’s 17.6 pounds), whereas the control group had gained 0.9 kilogram.

Brain scans show the change in pictures. The experimental group had fewer food cravings as well, which suggests what their brains perceived as pleasurable had changed. After 6 months, brain scans of a set of study volunteers showed that the reward centers of their brains became more active in the intervention group in response to pictures of grilled chicken, whole-wheat sandwiches and fiber cereal. Meanwhile that group’s brains became less responsive to images of french fries, fried chicken, chocolate candies and other fattening foods. They actually had learned to crave health food, and ignore junk food.

Personalized diets. We know that weight management is complex. We keep finding special circumstances that affect various people differently. For example, it has been well established that the majority of individuals who are obese are prediabetic — they secrete proportionately higher levels of insulin. This so-called insulin resistance leads to a host of other metabolic problems, such as increased risk of heart attack or developing type 2 diabetes. When we placed such people on a six-month iDiet program featuring our proprietary ratios of protein and fiber, nutritious vegetables and fruit, and fewer fast carbohydrates and a lower glycemic index, we found that they lost more weight than they could on a higher-carbohydrate diet (in addition to not being hungry, and not succumbing to cravings). People with low insulin levels, in contrast, did equally well on diets that were equally low in calories but higher in carbohydrates.

Tears and success. Despite the fact that the investigation described earlier was six months long and required active participation, only 11 percent dropped out. This is unheard of in commercial diet plans, which usually lose more than half their participants after just a few weeks. Some subjects even cried at the research team’s final visit because they did not want to say goodbye. In the words of one participant, “the science worked.”

Would you like to experience this yourself?