Think Type 2 diabetes’ high blood sugar levels are caused by drinking sodas and eating too many refined carbs? It’s not that simple. “In reality, a big problem is fat,” says Neal Barnard, MD, an adjunct associate professor at George Washington University School of Medicine and author of Dr. Neal Barnard’s Program for Reversing Diabetes (Rodale, 2007). Barnard is one of a growing number of experts who emphasize purging excess fat (both unhealthy fats from our diet and stored fats from our tissue) as a means of regulating blood sugar without the use of drugs.
By the numbers
8 percent of Americans with diabetes
57 million American adults with prediabetes
44.1 million estimated number of Americans who will have diabetes by 2034
Recent research backs up this approach: According to a landmark 1999 study of 3,200 people at high risk of developing diabetes, sustaining modest (7 percent) weight loss by eating a low-fat, moderate-carbohydrate diet and doing 150 minutes of moderate-intensity aerobic exercise a week can reduce diabetes risk twice as well as the leading diabetes drug, metformin. (A 10-year follow-up found that the lifestyle group was still twice as likely to have avoided diabetes). Other research suggests cutting animal fat in particular, via low-fat vegetarian or vegan diets, may work to reverse Type 2 diabetes, helping those on medication to lessen the amount they take and eventually stop taking medication altogether. Meanwhile, recent (and controversial) studies have linked blockbuster diabetes drug Avandia to a 43 percent increased risk of heart attacks and a 47 percent increase in bone fractures.
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How does blood sugar uptake work anyway?
Bite an apple and, if you are healthy, here’s what happens: Specialized beta cells in the pancreas sense the glucose in your blood and squirt out insulin. The insulin attaches to receptors on your muscle cells, much like a key slipping into a lock, and opens the door, ushering in glucose for use as fuel
In Type 1 diabetes (a largely genetic autoimmune disorder in which immune cells attack the pancreatic beta cells) the body ceases to produce insulin. In essence, the key is lost. But in prediabetes (a condition diagnosed when blood sugar reaches levels high enough to damage delicate tissues in the eyes, nerves, and joints) and in Type 2 diabetes (which makes up more than 90 percent of diabetes cases and also is largely attributed to lifestyle choices) the problem tends to be on the receiving end. “Your beta cells are functioning and you have all this insulin in your system, but for some reason, the insulin cannot get that glucose into your cell,” explains Bonnie Jortberg, RD, a diabetes educator with the University of Colorado in Denver. The cells have become “insulin resistant.” As a result, excess sugar (a source of oxidative stress in the body) builds up in the bloodstream, wreaking havoc on internal tissues. Meanwhile, the muscle cells (where that sugar belongs) starve, prompting fatigue.
“The saturated fat that builds up in the cells is very much like chewing gum in a lock,” explains Barnard. “It interferes with insulin’s intracellular signaling process.” Studies have shown that high levels of fat circulating in the blood stream of even lean, young people can interfere with cell signaling and prompt insulin resistance within hours.
To make matters worse in the long term, excess stored fat, or adipose tissue, has a metabolic life of its own, emitting proteins that influence appetite and fat metabolism, cause inflammation, and interfere with insulin action, setting up a vicious cycle of weight gain and worsening blood sugar. “Fat used to be considered an inert storage organ, but we now understand this tissue is producing hormones and other substances that have a huge impact on our organs,” says Preeti Kishore, MD, an endocrinologist with Albert Einstein College of Medicine in New York. Too much dietary fructose, whether in the form of high fructose corn syrup or honey, also contributes significantly to stored fat, says Bob Rountree, MD< Delicious Living’s medical editor, so it’s wise to go easy on sweets as well.
This notion of stored fat as culprit has caught on so much in recent years that many diabetics have turned to gastric-bypass surgery. A 2009 review of 600 studies showed 78 percent of patients had a complete resolution of their diabetes after surgery. (Follow-up studies are underway to determine how long that remission lasts.) But Barnard and others insist there’s a better way.
Healthier fats, slower carbs
There remains much controversy about just how much diabetics should cut back on dietary fat, with some advocating an all-out vegan approach, while others recommend a Mediterranean diet rich in “good fats.” However, many experts believe shifting to a plant-based diet is a critical first step. One 2009 study found that blood sugar levels of Type 2 diabetics following a vegan diet of 10 percent of calories from fat, 15 percent protein, and 75 percent unrefined carbs (with no calorie limit) for 74 weeks improved considerably more than those following American Diabetes Association (ADA) guidelines that cut calories by 500 to 1,000 and more strictly limited carbohydrates. Another study of 60,000 men and women in the United States and Canada found diabetes prevalence among vegans to be just 3 percent.
A longtime vegan, Barnard recommends avoiding animal products and going easy on most vegetable oils, which often contain saturated fat along with “good fats” (for instance, olive oil is 13 percent saturated fat). On the other hand, some in the medical field have expressed concern that cutting out animal products can rob people of omega-3 fatty acids, abundant in fish, grass-fed beef, and eggs. Omega-3s actually may enhance insulin sensitivity and protect against heart disease. Another concern: “A vegan diet may be beneficial, but it’s just so hard to follow in the long-term,” says Jortberg.
A good basic guideline, she says: Stick to a plant-based meal plan that goes easy on animal products. Limit oils and fat to 30 percent of your diet (7 percent saturated), and choose healthier fats such as omega-3s, and coconut and olive oils.
What about carbohydrates? Eating too many refined carbs can certainly overtax the pancreas to the point it has trouble producing insulin. But a diet very low in carbs tends to lead people to eat excessive dietary fat. The ideal compromise, experts say: Opt for low-glycemic index carbohydrates like whole grains (such as oats, brown rice, and quinoa) and fibrous vegetables such as beans, lentils, and sweet potatoes. These convert to glucose more slowly, giving the pancreas a chance to slowly catch up on insulin production.
