A perspective article challenges the 'energy balance model,' which says weight gain occurs because individuals consume more energy than they expend. According to the authors, 'conceptualizing obesity as a disorder of energy balance restates a principle of physics without considering the biological mechanisms underlying weight gain.' The authors argue for the "carbohydrate insulin model," which explains obesity as a metabolic disorder driven by what we eat, rather than how much.
Public health messaging exhorting people to eat less and exercise more has failed to stem rising rates of obesity and obesity-related diseases. The energy balance model, which says weight gain is caused by consuming more energy than we expend, restates a principle of physics without considering the biological mechanisms driving weight gain.
The carbohydrate-insulin model makes a bold claim: overeating doesn't cause obesity; the process of getting fat causes overeating. The current obesity epidemic is due, in part, to hormonal responses to changes in food quality: in particular, high-glycemic load foods, which fundamentally change metabolism. Focusing on what we eat rather than how much we eat is a better strategy for weight management.
Statistics from the Centers for Disease Control and Prevention (CDC) show that obesity affects more than 40% of American adults, placing them at higher risk for heart disease, stroke, type 2 diabetes, and certain types of cancer. The USDA's Dietary Guidelines for Americans 2020 -- 2025 further tells us that losing weight "requires adults to reduce the number of calories they get from foods and beverages and increase the amount expended through physical activity."
This approach to weight management is based on the century-old energy balance model which states that weight gain is caused by consuming more energy than we expend. In today's world, surrounded by highly palatable, heavily marketed, cheap processed foods, it's easy for people to eat more calories than they need, an imbalance that is further exacerbated by today's sedentary lifestyles. By this thinking, overeating, coupled with insufficient physical activity, is driving the obesity epidemic. On the other hand, despite decades of public health messaging exhorting people to eat less and exercise more, rates of obesity and obesity-related diseases have steadily risen.
New research has found that children who eat more fruits and vegetables have better mental health (Hayhoe et al., Cross-sectional associations of schoolchildren’s fruit and vegetable consumption, and meal choices, with their mental well-being: a cross-sectional study). The study is the first to investigate the association between fruit and vegetable intakes, breakfast and lunch choices, and mental wellbeing in UK school children. The research team studied data from almost 9,000 children in 50 schools. They found that the types of breakfast and lunch eaten by both primary and secondary school pupils were significantly associated with wellbeing.
According to lead author Dr. David Ludwig, Endocrinologist at Boston Children's Hospital and Professor at Harvard Medical School, the energy balance model doesn't help us understand the biological causes of weight gain: "During a growth spurt, for instance, adolescents may increase food intake by 1,000 calories a day. But does their overeating cause the growth spurt or does the growth spurt cause the adolescent to get hungry and overeat?"
In contrast to the energy balance model, the carbohydrate-insulin model makes a bold claim: overeating isn't the main cause of obesity. Instead, the carbohydrate-insulin model lays much of the blame for the current obesity epidemic on modern dietary patterns characterized by excessive consumption of foods with a high glycemic load: in particular, processed, rapidly digestible carbohydrates. These foods cause hormonal responses that fundamentally change our metabolism, driving fat storage, weight gain, and obesity.
1. When we eat highly processed carbohydrates, the body increases insulin secretion and suppresses glucagon secretion.
2. This, in turn, signals fat cells to store more calories, leaving fewer calories available to fuel muscles and other metabolically active tissues.
3. The brain perceives that the body isn't getting enough energy, which, in turn, leads to feelings of hunger.
4. Metabolism may slow down in the body's attempt to conserve fuel. Thus, we tend to remain hungry, even as we continue to gain excess fat.
To understand the obesity epidemic, we need to consider not only how much we're eating, but also how the foods we eat affect our hormones and metabolism. With its assertion that all calories are alike to the body, the energy balance model misses this critical piece of the puzzle.
Adoption of the carbohydrate-insulin model over the energy-balance model has radical implications for weight management and obesity treatment. Rather than urge people to eat less, a strategy which usually doesn't work in the long run, the carbohydrate-insulin model suggests another path that focuses more on what we eat.
YOU ARE WHAT YOU EAT! NOT HOW MUCH YOU EAT...