Many overweight adults can't seem to lose weight no matter what they try. The problem may not lie in their calorie counts but their very cells: Increasing numbers of Americans, leading nutritionists say, are insulin-resistant. That is, their bodies no longer properly use the hormone insulin to process the food that's eaten. Net result: The body hangs on tight to the fat that's already there.
A stubborn inability to lose weight because of insulin resistance is a complicated but common problem, says integrative nutritionist Beth Reardon, director of nutrition for Duke Integrative Medicine, part of the Duke University Health System. If you're fighting the scale, she adds, you may be among the 79 million American adults who have or are heading toward prediabetes, a syndrome of insulin-related challenges that usually leads to diabetes unless health changes are made.
In 2010, 1.9 million new cases of full-blown diabetes were diagnosed, according to the Centers for Disease Control. Indeed, diabetes and obesity are so related that some health experts have coined the descriptor diabesity.
Why you may not be losing weight
When we eat, the food is broken down into glucose (blood sugar), the body's main energy source. As blood flows through the pancreas, this organ detects the high levels of glucose and knows to release insulin, a hormone that it produces in order to allow the cells throughout the body to use the glucose. The cells have insulin receptors that allow glucose to enter. Then the cell either uses the glucose to make energy right away or stores it as a future energy source.
For some people, though, this system has gone haywire. The cells' insulin receptors have pretty much stopped acknowledging the insulin, which means the cells don't get the glucose. Instead, the glucose builds up in the blood, where the pancreas notes the escalating glucose levels and pumps out still more insulin in response.
"The cells are starving because the fuel they need isn't being absorbed at the insulin receptor site on the cell," Reardon says.
So what does the body do in response? It hangs on fiercely to the energy stores -- fat -- it already has. And any glucose the cells do manage to absorb goes straight into storage -- as still more fat.
You can't lose weight because your body is in survival mode.
This whole process builds slowly over years. What triggers it in the first place? Experts believe that for many people, the problem stems mainly from a diet overloaded with simple carbohydrates -- bread, pasta, pizza, pastries, crackers, chips and other processed snack foods, sweetened beverages, corn syrup, and other quickly-digested sugars and starches. In other words: the typical modern Western diet. Faced with constant, quick hits of easily digested energy sources, the pancreas keeps pumping out insulin to help the energy get into the cells, but the overwhelmed cells finally say, "Enough!" and stop paying attention.
More warning signs of insulin resistance
This kind of stubborn fat doesn't happen in isolation. The difficulty losing weight almost always occurs along with most of the following warning signs that you may be insulin resistant:
Weight gain centered in the middle -- "belly fat" -- measuring greater than 40 inches for a man or 35 inches for a woman
A body mass index (BMI) in the overweight or obese zones
A tendency to crave carbohydrates (as the starving cells tell the brain to give you more, more, more!)
Frequent fatigue, especially right after eating
Foggy thinking (because glucose is the preferred energy source for the brain, and the brain's cells, too, are starving for glucose)
High glucose levels, as measured by an oral glucose tolerance test (OGTT) or fasting plasma glucose test (FPG) (The latter test isn't routinely offered in clinical practices.)
High fasting and timed insulin levels, which are measured as part of the OGTT
High blood pressure (135/85 or above)
Low levels of "good" HDL cholesterol (below 40 mg/Dl for a man, below 50 mg/Dl for a woman)
High triglyceride levels (150 mg/Dl or above)
Together, this constellation of symptoms is known as "metabolic syndrome," or "syndrome X." Even though there seems to be a genetic predisposition for some people, insulin resistance that leads to type 2 diabetes largely depends on lifestyle. "Anyone can eat his or her way to diabetes," Reardon says. "Diabetes is particularly lifestyle and diet-driven."
What can help this stubborn weight come off
The good news is that you can reverse even this super-stubborn weight loss associated with prediabetes. "It's all about babying the pancreas," Reardon says.
Start moving more. Sure, you can think of it as burning calories, but your real goal by exercising is to engage the metabolism. As you work your muscles, you increase the number of enzymes that are looking for glucose as a fuel source (instead of just turning it into fat).
Aim for 30 to 45 minutes of moderate exercise (like walking) five to seven days a week. Bonus: Heavier people burn more energy when performing the same amount of exercise as leaner people, according to recent research at the National Institute of Diabetes and Digestive and Kidney Diseases.
Do a "whiteout." You don't need a degree in nutrition to make things easier on your cells. Start with the simple step of eliminating white sugar, white flour, and white rice from your diet. This automatically reduces the amount of quickly digested carbohydrates you take in.
Move away from wheat. You've surely heard that 100-percent whole wheat is better for you than processed white, but there are better grains to help you cope with stubborn fat. "All modern wheat varieties are different from the kinds our bodies evolved to process," Reardon says. The man-manipulated wheat we eat today is lower in fiber and too digestible, affecting glucose levels too quickly.
Explore the wide world of good grains. You don't have to give up all breads and cereals. But you do want to move toward whole (intact), unrefined grains, which offer more fiber and other nutritional benefits. Luckily a huge range of whole, unprocessed, unrefined alternatives to wheat, corn, and rice is now widely available at supermarkets, and even at food wholesale warehouses. Look for so-called "ancient grains" such as spelt, quinoa, amaranth, barley, brown rice, and teff.
Get carb-choosy about all your food. Carbs aren't just in grains. Eat fruits and vegetables in whole forms, rather than as purees and juices, so the body has to work harder to get the glucose in them. When you can, be sure to eat the peels too, to get more fiber.
Shop outside the box. Because countering insulin-resistance weight gain depends on every mouthful, give up most packaged foods. They tend to be high in fat and chemicals, low in fiber and other nutrients. Shop the grocery perimeter instead, where most whole food is located.
Learn about (and lower) inflammation, a component underlying many common chronic diseases. This dangerous process undermines the general health of cells. What helps: Adding healthy sources of anti-inflammatory proteins (especially coldwater fish like salmon or omega-3 fortified eggs), walnuts, blueberries, flax, olive oil, green tea, red wine, and spices like cinnamon and turmeric. Replace such fats as butter and lard.
As a last resort, ask a doctor about medication that can help. Metformin is sometimes prescribed for very stubborn cases of the inability to lose excess weight because of insulin resistance, Reardon says. This drug helps control the amount of glucose in your blood; it's only effective in connection with dietary changes and exercise.
"Insulin resistance is preventable, and with these steps someone suffering from it should notice almost immediate changes," Reardon says. Lethargy, fatigue, and foggy thinking start to lift. You'll have more energy. And the pounds will finally start to drop.