Despite the common observation that obesity runs in families, genetic research shows that the habits you inherit from your family are more important than the genes you inherit. Obesity genes account for only 5 percent of all weight problems. So, we have to wonder, what causes the other 95 percent of weight problems?
We are seeing an obesity epidemic in America today. More than 70 percent of Americans are overweight. Whereas in the 1980s not one state had an obesity rate over 20 percent, now only one state has an obesity rate under 20 percent! It is the single most important public health issue facing us.
If genes do not account for obesity, perhaps it is our high-fat diet that is to blame. That has been the common belief in our society since nutritional low-fat guidelines were pushed upon us in the 1970s. Fat contains 9 calories per gram, so it would seem logical that eating more fat (and more calories) would make you gain weight. But that’s not what the science reveals.
What the research tells us about dietary fat
Pioneering research by Harvard Medical School’s David Ludwig reveals the reason that low-fat diets do not work, and identifies the true cause of obesity for most Americans. In a study published in the Journal of the American Medical Association, Dr. Ludwig points out that careful review of all the studies on dietary fat and body fat — such as those done by Dr. Walter Willett of the Harvard School of Public Health — have shown that dietary fat is not a major determinant of body fat.
Let me repeat that.
Dietary fat is not a major determinant of body fat.
Want more proof? The Women’s Health Initiative found that 50,000 women on low-fat diets had no significant weight loss. Yet another study looked at people who followed four different diets for 12 months, and found no dramatic differences between those who followed low-fat, low-carb and very low-carb diets.
The question, then, is, “Why aren’t we seeing any significant effects or differences from these various diets?” The main reason, Dr. Ludwig suggests, is that we are looking for answers in the wrong place.
The future of treating obesity and weight is in personalizing our approach. This is the approach I wrote about in my book UltraMetabolism. It’s called nutrigenomics. It is the science of how we can use food to influence our genes and personalize our approach to health.
A better way to diagnose and treat obesity
Over the last 15 years, I have tested almost every one of my patients using a test that most doctors never use. It is even harder to find in the research, except in this pioneering work by Dr. Ludwig.
This test is cheap and easy to do, and is probably the most important test for determining your overall health, the causes for obesity and your risk of diabetes, heart disease, cancer, Alzheimer’s and premature aging. Yet it is a test your healthcare provider probably does not perform, does not know how to interpret and often thinks is useless.
Thankfully, Dr. Ludwig’s research brings this critical method of diagnosing the cause of obesity and disease to the forefront. In two recent studies, he found that the main factor that determines changes in body weight and waist circumference (also known as belly fat) is how your body responds to any type of sugar, carbohydrate or glucose load.
The most important test to determine this doesn’t measure your blood sugar or cholesterol. It tests your insulin level. You have to check it after drinking a sugary beverage that contains at least 75 grams of glucose. This test has shown me more about my patients than any other test and helps me personalize a nutritional approach for them.
The ins and outs of insulin
Its usefulness is now being borne out in this research by Dr. Ludwig and his colleagues. In one study, for example, Dr. Ludwig and his colleagues followed 276 people for six years. They performed a glucose tolerance test at the beginning of the study and looked at insulin concentrations 30 minutes after the people consumed a sugary drink. This gave the researchers a rough estimate of whether they were high or low insulin secretors.
During the course of the study, they looked at body weight and waist circumference. They found that those who were the highest insulin secretors had the biggest change in weight and belly fat compared to the low insulin secretors. And people who were high insulin secretors and ate low-fat diets did even worse.
This makes perfect sense, because insulin does two things:
1. It stimulates hunger.
2. It is a fat storage hormone, which makes you store belly fat.
After you eat a high-carbohydrate meal, your insulin spikes and your blood sugar plummets, making you very hungry. That is why you crave more carbs, more sugar and eat more over the course of the day.
Dr. Ludwig also found that the patients who ate a low glycemic load diet — which lowers blood sugar and keeps insulin levels low — had much higher levels of HDL “good” cholesterol and much lower levels of triglycerides. It appears that the best way to address your cholesterol is not necessarily to eat a low-fat diet, but to eat a low glycemic load diet, which keeps your blood sugar even.
I encourage you to ask your physician to do a glucose tolerance test and measure your insulin and blood sugar at 30 minutes, one hour and two hours after drinking a sugary beverage to get the best picture of your insulin profile.
If you are a high insulin secretor and your insulin goes over 30 at a half hour, one hour or two hours, you produce too much insulin and need to be sure you adhere to the low glycemic load, whole-foods, unprocessed diet, which I describe in UltraMetabolism. This is essential if you want to lose weight and achieve lifelong vibrant health.
The bottom line is simply this …
If you want to fit into your jeans, you have to fit into your genes.
To your good health,
Mark Hyman, M.D.