Do you actually lose weight by eating less or more? Is it really possible to lose weight if you eat more? How does this work?

Michael Herschel Greger is an American physician, author, and professional speaker on public health issues, best known for his advocacy of a whole-food, plant-based diet, and his opposition to animal-derived food products.

Let’s listen to Dr. Greger

What happens if you have people adding fruit to their regular diet? Three apples and pears a day, as snacks between meals on top of whatever else they were eating. The fruit is low in calories, but not zero. So, if you add food to people’s diet, even healthy foods, won’t they gain weight? No, they lost a couple of pounds. Maybe it was all that fibre? If you remember, we’ve learned that our gut bacteria can create anti-obesity compounds from the fiber. That’s why they also had a cookie group; three pears, three apples, or three cookies with enough oats in them to have about the same amount of fibre as the fruit.

Despite the fibre, adding cookies to one’s diet does not lead to weight loss. They think the weight-reducing secret of fruit is its low energy density, meaning that you get a lot of food for just a few calories and so it fills you up. Energy density is a relatively new concept that’s been identified as an essential factor in body weight control in both adults and children and adolescents. Energy density is defined as the number of calories per unit weight of a food or beverage. Water, for example, provides a significant amount of weight without adding calories. And so is fibre. Thus, foods high in fibre and water are generally lower in energy density. On the other hand, since dietary fat provides the greatest amount of calories per unit weight, foods high in fat are generally high in energy density. The CDC offers some examples. High energy-dense foods like bacon – have lots of calories in a small package. Medium energy-dense food is like a bagel, and fruits and vegetables typify a low-density food. In general, the lower, the better, with two exceptions.

Soda is so heavy so that by energy density, it looks less harmful than it is. And nuts have so much fat. They appear less healthy than they are. Other than the ones mentioned above, the science supports a relationship between body weight and energy density such that consuming diets lower in energy density may be an effective strategy for weight control. This is because people tend to eat a consistent weight of the food. So, when there are fewer calories per pound, calorie intake is reduced.   

A small drop in energy density can lead to a small drop in weight, and the higher the decrease in energy density, the greater the weight loss.

Energy density can be reduced in a variety of ways such as the addition of fruits and vegetables to recipes, or by lowering the sugar or fat content. And indeed, that’s how we evolved. We were eating predominantly low energy density foods such as vegetables, fruits, and starch-filled roots like sweet potatoes, plants, and tubers.

The first study to emphasize how vegetables and fruits could affect food intake and energy density was conducted more than 30 years ago. 

Researchers were able to cut people’s caloric intake nearly in half. From 3000 calories a day, it went down to 1570 without cutting portions. It was done just by substituting less calorie-dense foods, which means lots of fruits,  whole grains and beans, and vegetables, compared to a high energy density meal with lots of sugar and meat. Nearly half the calories, but they enjoyed the meals just as much. They tried this in Hawaii by putting people on a traditional Hawaiian diet. They were provided with all the plant foods they could eat. This resulted in a loss of an average of 17 pounds in just 21 days, resulting in better triglycerides, cholesterol, blood pressure, and blood sugar. Caloric intake got reduced by 40 percent, but not by eating less food. By eating more food – four pounds of food, they lost 17 pounds in 21 days. But since plants tend to be so calorically dilute, one can stuff oneself without getting the same kind of weight gain.   

And the energy density of foods has gained attention in weight management. It not only allows people to eat satisfying portions while limiting calories, but also reductions in energy density gets associated with improved dietary quality. For example, lower energy-dense diets are associated with a low risk of pancreatic cancer. Lower energy density foods tend to be healthier foods, so we get the best of both worlds.