Last month we discussed the challenge of helping overweight clients lose and then keep off excess body fat stores and how data from the National Weight Control Registry and similar data from other countries can provide some insights. Of course, knowing what the relatively small percent of people did to achieve their goal of losing and then keeping off excess body weight can not necessarily be generalized to everyone. Perhaps these individuals had rare traits that allowed them to accomplish an important goal that few others appear able to do, especially over the long term. Anyone who has lost weight and tried to keep it off over the long term knows that one of the greatest challenges is both an increased appetite that persists for most until the weight is regained, coupled with an apparently slower metabolic rate.
However, most research suggests that the widely held belief in the role of a markedly slowed metabolic likely play at most a very minor role (1). In addition, the widespread assumption that one key to long term weight control is regular exercise seems increasingly questionable. Indeed, one of the more surprising findings from the recent observational study of those who lost and kept off a lot of weight was that regular exercise appears to not play a significant role in preventing weight regain for most people who achieve long-term weight control (2). This same study showed few relied on prescription drugs or OTC drugs or supplements for long term weight loss success.
What Works for LT Weight Control?
It has long been assumed that the far lower levels of obesity in hunter gatherers and third world countries is due to the greater activity energy expenditure (AEE) in those cultures. However, there is growing data from the Tsimane, the Kalahari Bushman, and rural Nigerian women have all shown little difference in AEE. Most Africa-American are obese or overweight and weigh on average 57lbs more than do age matched living in rural Nigeria. The mean BMI of the African-American women was 30.8 compared to only 22.8 for the mean Nigerian woman with double the average fat mass (3). While obesity is often blamed on inactivity in modern societies there is growing reason to suspect the impact on AEE on BMI is not a major factor. Indeed, the average AEE of adult Americans has changed little since 1970 and yet the prevalence of obesity has increased markedly over the past 50 years in the United States. I hunter-gatherer populations peak body weight occurs in their 20s. However, in modern societies average BMI and % body fat increase in most people until their 50s and 60s and typically peaks in late 50s to early 70s.
Diet is Most Important Promoter of Obesity
The data from national weight control registries suggests that successful weight control depends in large part in consuming a diet that has a lower energy density (ED), more fiber, and less fat and refined carbohydrates.
More processed and refined foods that are calorie dense with little or no fiber appear to promote weight gain over time. Why? Such diets appear to provide less satiety per calorie. Simply put foods high in fat, refined carbohydrates, and low in fiber may taste great but they are also less filling. The same number of calories from mostly whole minimally processed plant foods provide more satiety per calorie than do ED highly processed foods loaded with concentrated fat and/or refined carbohydrates and little fiber. It is becoming increasingly clear that obesity is not a disease caused by a lack of will power or sloth. It is largely a biological problem caused by genes and a toxic or obesogenic diet. And while it is tempting to put most of the blame on “fat” genes it is hard to explain the marked increase in obesity over the past 5 decades largely on genes. As the old saying goes genes may load the gun, but it is the environment that pulls the trigger.
Reduced ED Not Main Promoter Of Obesity Pandemic
If one looks around the world, it does appear the typical modern Western diet is likely promoting a worldwide pandemic of obesity. There are many theories as to why the modern diet promotes weight gain and leads most Americans to become overweight or obese by middle-age, if not sooner. So while we have known that the typical modern diet promotes obesity it is not simply increased ED. The truth is in the USA obesity rates have increased markedly while the average ED, ratio of fat to protein to carbohydrate and fiber content have changed little over the past 50 years.
The one dietary variable that correlates the most with excess ad libitum energy intake and the rise in obesity rates in the United States is not the average ED, fiber intake, change in the ratio of fat to protein to carbohydrate. Back in the 1950s and 1960s when about 3/4 of adults were normal weight today it is fewer than 1/3) only about 10% of daily energy intake came from beverages. Today, the typical American consumes 20 to 30% of their day’s energy from beverages. While beverage calories tend to have a lower energy density than solid foods most research in animals and people show that beverage calories provide far less satiety per calorie. The result is dry sugar, which is about 10X as energy dense as sugar water provides less satiety per calorie. If the goal of reducing ED is to increase satiety per calorie so people can feel satiated on a lower energy intake, then the worst way to reduce ED is to consume more beverage calories. An apple is a high satiety per calorie food choice, but apple juice with the same ED provides far less satiety per calorie and promotes weight gain. Replacing sugar containing beverages with those with noncaloric sweeteners aids weight loss by cutting beverage calorie intake. Adding noncaloric sweeteners to solid foods has little or no impact on satiety per calorie.
Bottom Line: The key to long-term weight control appears to be adopting a diet that provides more satiety per calorie. That means more whole minimally processed plant foods and less ED highly processed foods load with fat and/or refined carbohydrates. And it also means eliminating most beverage calories. And yes, this includes fruit and vegetable juices.
By James J. Kenney, PhD, FACN
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