Intermittent Fasting - A Highly Successful Approach to Weight Loss
PART 1 - DEBUNKING OUTDATED THEORIES OF LOW-FAT AND CALORIE-RESTRICTION DIETS
According to the Centers for Disease Control (CDC), over 71% of Americans are overweight. So it shouldn’t be surprising that it seems like a new diet comes along every day. For years, counting calories was thought to be one of the best solutions for weight loss: restrict your calories - and lose weight. Another popular theory proposed that low-fat was the way to go. However, these approaches are now being rethought, and more successful strategies - like intermittent fasting - are being proven to be much more effective.
THE RISE OF THE LOW-FAT DIET
So how did diets insisting that low-fat is the way to go become popular in the first place? Back in 1958, an American scientist named Ancel Keys started a study called the Seven Countries Study, which examined the association between diet and cardiovascular disease in different countries. The study concluded that the countries where fat consumption was the highest had the highest prevalence of heart disease, supporting the theory that dietary fat causes heart disease. The problem was - his research was flawed - he only used data from the countries that supported his theory and ignored countries with high consumption of fat that disproved his hypothesis. Regardless, his study received enormous media attention and had a significant influence on the dietary guidelines of the next few decades. These dietary guidelines - adopted in the 1977 Dietary Goals for the United States - eventually contributed to an overall decline in health, specifically a near tripling of the national obesity rate along with related diseases including type 2 diabetes.
Another reason behind the rise in popularity of the low-fat diet: is the influence of the sugar industry. According to an article published in the New York Times, “The sugar industry paid scientists in the 1960s to play down the link between sugar and heart disease and promote saturated fat as the culprit instead.” The article goes on to say that at that time, a trade group known as the Sugar Research Foundation paid Harvard scientists to publish a paper that “minimized the link between sugar and heart health and cast aspersions on the role of saturated fat.”
THE POPULARITY OF THE CALORIE-RESTRICTING DIET
In addition to reports that people should follow a low-fat diet, for years the diet industry recommended restricting caloric intake. A highly popular TV show - The Biggest Loser - seemed to support this theory. Contestants shed hundreds of pounds by counting calories and undertaking highly intensive exercise regimens.
One scientist decided to follow the “Biggest Loser” contestants for six years after their appearances on the show, beginning a project that became the first to measure what happened to people over six years after they had lost large amounts of weight with intensive dieting and exercise. And the results were depressing - most of them gained all of their weight back and in some cases more - demonstrating just how hard the body fights back against weight loss. Unfortunately, the research suggests that sustaining weight loss, particularly through a calorie-restricted diet focused on small meals throughout the day - is particularly difficult.
This calorie-restrictive model of dieting causes a reduced metabolic rate also known as “total energy expenditure” or “TEE”. This means that your body naturally burns less calories throughout the day. As energy expenditure gets shut down with fewer calories, people tend to feel more fatigue, their heating system gets turned down (i.e. the body feels cold), and their muscles get less energy (i.e. exhaustion). The body is smart - if it feels like it’s getting fewer calories than needed - it will adjust to what it’s getting to survive. In other words, less calories in means less calories out.
WEIGHT LOSS - IT’S A MATH EQUATION AND A HORMONE EQUATION
The main reason that keeping weight off is so challenging is that the human body is designed to protect itself when it sheds weight by increasing our urge to eat while slowing down our total energy expenditure and more efficiently storing fat. A BMJ study set out to determine if different levels of carbohydrates in the diet could prevent these metabolic changes from occurring, so that weight loss might stay off. The researchers based this hypothesis on the carbohydrate-insulin model of obesity, which posits that “high insulin levels that result from eating a high glycemic load diet (i.e., highly processed carbohydrates like refined bread, crackers, cookies, and sugars) cause energy from the food to be stored more easily as fat, and may increase hunger and food cravings, lower energy expenditure, and promote weight gain.” Patients who were on a low-carb, high-fat diet (with the same amount of calories and energy expenditure) saw an increase in their energy expenditure. Their metabolism increased so they they burned more calories throughout the day. The study concluded that “a focus on restricting carbohydrates, rather than calories, may work better for long-term weight control.”
So the bottom line: the types of calories one consumes are equally as - or arguably more - important than the number of calories because of their impact on insulin. The key is reducing insulin and the impact on downstream hormones (such as leptin and ghrelin) that determine appetite and a body’s tendency to burn or store fat.
INTERMITTENT FASTING - A TOOL FOR SUSTAINABLE WEIGHT LOSS
In addition to monitoring the kinds of calories you consume, one of the most profound ways to impact insulin is through intermittent fasting. Whereas calorie restriction is a consistent pattern of reducing your average daily caloric intake, fasting regimens focus primarily on your eating frequency. According to an article published by Harvard Medical School, “Between meals, as long as we don’t snack, our insulin levels will go down and our fat cells can then release their stored sugar, to be used as energy. We lose weight if we let our insulin levels go down. The entire idea of intermittent fasting is to allow the insulin levels to go down far enough and for long enough that we burn off our fat.”
We explain the concept of intermittent fasting - including information on how and why it works, research supporting this approach as well as several tips and tricks for successful fasting - in our second post in this series. In the meantime, I’d be happy to tell you more about intermittent fasting as well as answer any questions you have. Just give the office a call at 425-209-1060. You can also visit our Medical Weight Loss page to learn more about our program.
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