You’d think it’d be all about super-sized portions…but there are actually multiple factors concerning the epidemic of obesity, a trend that has led to a corresponding increase in heart disease and type 2 diabetes. Researchers continue to actively study a variety of possible causes. Evidence has been mounting for one theory called the protein leverage hypothesis. A new study from researchers at University of Sydney’s Charles Perkins Centre in Australia gives more support for this hypothesis.
Searching for Protein in Processed Foods
There are two parts to the protein leverage hypothesis. The first part is that the human evolution has favored a diet that primarily regulates protein. Protein is the basic building block for human cells. Cell growth and repair are based on having enough protein in the diet. The second part is that if you don’t get enough protein in your diet, you’ll start to crave energy-dense foods.
In the diets of developed countries like the U.S. and Australia (usually referred to as the Western Diet), calories often come from highly processed foods. To get enough protein from these foods you need to eat a lot of calories and that means lots of fats and carbohydrates. Excess calories from these protein-diluted foods lead to obesity. The protein leverage theory suggests that the search for proteins in processed foods contributes significantly to obesity, heart disease and diabetes.
Protein for Breakfast Is Key
The University of Sydney study is published in the journal Obesity. The research team looked at one year of diet history in 9,341 people with an average age of 46. They used diet histories from the Australian National Nutrition and Physical Activity Survey. The study found that these people got about 18 percent of their calories from protein, 43.5 percent from carbohydrates and about 31 percent from fats. The study also found that people who consumed more protein for breakfast (first meal of the day) needed to take in less calories during the rest of the day. Those who ate less protein for their first meal of the day ate more food during the day to make up for the deficit. These foods were calorie and energy dense foods high in saturated fats, sugars, salt, or alcohol. Because these foods lack protein, they ate more calories to reach the body’s protein demand.
The study suggests that the first meal of the day should be higher in protein from foods including milk, eggs, fish, lean meat, soy, legumes, and beans. These are also the best sources for protein at any meal. Processed foods are often favored over these foods because they are high in flavor and calories for energy. They are also heavily marketed, convenient, and often less expensive compared to whole foods. Marketers and manufacturers know that a diet high in processed foods increases overall appetite and consumption.
Processed Food: The Good and the Bad
According to the Department of Agriculture, processed food is any edible product altered from its natural state. That’s hard to avoid completely, especially if you shop at a supermarket, eat tuna salad, or cook with canned tomatoes. When you cook potatoes or rice, you’re (technically) eating processed food. Things get tricky and unhealthy when preservatives or other ingredients such as fat, sugar or salt are added to food. Packaged snacks such as crackers or chips that are easy to mindlessly munch on are highly processed foods that contain those hard-to-pronounce ingredients. Ultra-processed foods are frozen ready-to-eat meals such as pizza or meals packaged for microwave cooking.
The researchers noted that other factors driving the obesity epidemic include lack of physical activity and lack of sleep. But understanding how protein drives the human diet is a very important discovery that can be used to bring the obesity epidemic, diabetes and heart disease under better control.
