If you’re overweight and trying to lose a few pounds, you’ve probably been told to eat a low-calorie diet and limit your fat intake. But for some people, that approach doesn’t work. The needle on the scale stays glued to the same spot no matter how many times they skip the cream cheese on a morning bagel.
The obstacle might not be willpower. The lack of weight loss progress could be caused by the way the body reacts — or doesn’t react — to a critical metabolic hormone.
Insulin, which is secreted by the pancreas when you eat, tells your body’s cells that fuel (in the form of glucose, or sugar) is now available for immediate use. But in some cases, for a variety of reasons, the body’s cells don’t respond as they should. They remain closed off and ignore all that free-floating glucose, which must then be stored as fat instead. In insulin-resistant individuals, when the body’s cells ignore the first wave of insulin, the pancreas reacts by producing even more to try to get the cells to respond properly.
If this cycle continues over a long period of time, it can result in hyperinsulinemia — high levels of insulin in the body all the time. “Insulin resistance and hyperinsulinemia in the U.S are both highly prevalent, along with diabetes and obesity,” says Michael W. Lee, MD, an endocrinologist and weight management specialist at Scripps Clinic Center for Weight Management. These conditions can make losing weight more difficult, and they are more common as people get older.
A 2011 article authored by Dr. Lee and his colleague, Ken Fujioka, MD, director of the Center for Weight Management at Scripps Clinic, found that low-fat diets may not work as well in people who are insulin-resistant as they do for those with a normal metabolic response to insulin. In several clinical studies, when insulin-resistant subjects were assigned to a low-carbohydrate diet, they lost more weight than their counterparts on a low-fat diet, and they lost it faster.
Several risk factors may indicate insulin resistance:
- Being overweight, especially when excess weight is concentrated in the trunk and belly
- High fasting glucose levels
- Elevated blood pressure
- High blood levels of triglycerides and low levels of HDL (“good”) cholesterol
If you think you may be insulin-resistant — an indicator of metabolic syndrome or pre-diabetes — you should speak with your doctor.
One of the most reasonable, least restrictive forms of a low-carb diet is eating mainly foods that are low on the Glycemic Index (GI). A GI score is a measure of the effect that a given food has on blood sugar levels.
- High-glycemic foods (70 and above): These cause sudden and significant insulin spikes
- Mid-glycemic foods (56-69): These are foods with moderate insulin-raising effects
- Low-glycemic foods (0-55): These help keep insulin levels relatively low and steady
- Carbs that minimize blood sugar spikes: Beans and legumes, fresh or frozen fruits and vegetables, milk, yogurt
- Carbs that bring on blood sugar spikes: Most kinds of refined flour products including bread; bakery products; rice; breakfast cereals; and sugary drinks and fruit juices
Because foods are rarely eaten in isolation, and because factors like preparation and other foods consumed at the same time also affect insulin release, GI numbers are only generalizations.
Harvard University offers a simplified online glycemic index reference for people in the U.S., based on a much larger Australian database that contains many prepared and packaged foods unavailable here. There are also smartphone and tablet apps to track and manage the insulin impact of dietary carbs.
“Eating low on the glycemic index will work for anybody trying to lose weight, because you are less likely to consume excessive calories in the form of sugary beverages, fruit juices and simple carbohydrates,” says Dr. Lee. “Even if somebody is not insulin-resistant and doesn’t get additional weight-loss benefits from minimizing their intake of simple carbohydrates, it’s a reasonable and healthy way to eat.”
The key to weight loss, he points out, is consistency and sustainability. It is possible to lose weight and maintain that loss on any kind of reduced-calorie diet, as long as it allows foods that you like, so you can stick to it.
The experts at Scripps Clinic Center for Weight Management can help you create a personalized plan to achieve and maintain a healthy weight.