The United States is in the midst of obesity and Type 2 diabetes epidemics, one seemingly feeding the other. According to the , 71 percent of adults over the age of 20 are overweight, while 38 percent are obese. And the reports that 30.3 million Americans, or 9 percent of the population, has diabetes, while 84 million Americans age 18 and older have prediabetes.
Researchers have been trying for decades to find ways to help people avoid higher-than-normal blood sugar levels that can lead to Type 2 diabetes. They have created the Glycemic Index to help people understand how different foods affect their blood sugar levels, and helped people with high blood sugar levels understand what and when to eat and how much exercise to get. Now, researchers are out with a new study with findings that suggest the order in which people should eat foods to keep their blood sugar levels as low as possible. And it's completely at odds with how most restaurants serve their meals, not to mention how many home meals are served.
Avoiding the Blood Sugar Rollercoaster
The research team previously did a study of those with Type 2 diabetes, discovering that nutrient order during a meal has a major impact on glucose and insulin levels after the meal. So, if the same exact foods were being eaten at two mealtimes, simply rearranging the sequence in which foods were eaten could be the difference between a relatively sedate glycemic response (if a fiber-filled salad was eaten first), or a rollercoaster ride (if bread was eaten first).
This new study by the same researchers focused on those with prediabetes. (Per the stats above, the findings have relevance for 84 million Americans.) Study participants were given the same meal on different days but in one of three sequences:
Ciabatta bread (a carb with only 2.6 grams of fiber per serving) first followed 10 minutes later by skinless grilled chicken breast (a lean protein) and a salad (fibrous lettuce, tomatoes, bell peppers, red cabbage, with balsamic vinegar and olive oil).
The protein and salad first, followed 10 minutes later by the bread.
The salad first, followed 10 minutes later by the chicken breast and bread.
The researchers discovered that peak blood sugar levels were 46 percent lower when participants ate the chicken breast and salad first and the bread 10 minutes later. When they ate their salad first and followed with the chicken breast and carbs, their blood sugar levels still dropped by 44 percent.
These lowered glucose measures were evident 30 and 60 minutes after the meal. But blood glucose measures in the bread-first group were lower at 120, 150, and 180 minutes. After the initial blood glucose spike in response to carbs—typical among those with prediabetes—the body secretes as much insulin as it needs to drive glucose levels lower—sometimes much lower. It's that "carb coma" sensation.
"Starting a meal with carbs stimulates a bigger insulin response and leads to marked glycemic variability; that is, higher peaks and lower troughs," says the study's lead author, Alpana Shukla, MD, MRCP (UK), assistant professor of research in medicine and Director of Clinical Research at the Comprehensive Weight Control Center of .
Protein, fat, and fiber all slow gastric emptying, which may be one reason why consuming them before carbs lowers the glycemic response. The pancreas has more time to handle that blood sugar spike in a measured way.
"Fiber, more than even fat and protein, appears to play the leading role in dampening the post-meal glucose peak," says Shukla.
So, in this case, the salad is more important than the chicken breast or the dressing on the salad. She's quick to note, however, that the study was designed around real-world meal combos, not isolated macros.
Blood Sugar Volatility and Heart Health
So, what's the big deal with a blood glucose spike, anyway? After all, unless the spike is extreme, you can't even feel it—only the drop that comes later, if it's pronounced enough. First, if you have prediabetes, those volatile glucose excursions are setting the stage for full-on Type 2 diabetes. Over time, they can also contribute to coronary artery disease.
"Sharp blood sugar fluctuations, even among those who are not yet diabetic, are toxic for the endothelium," says Silvio Buscemi, M.D., a researcher and professor specializing in diabetes and clinical nutrition at the University of Palermo in Italy.
Blood Sugar Volatility and Weight Loss
Do those glucose and insulin spikes promote weight gain, too? That's more hotly debated. Remember, those three eating sequences were the same, calorie-wise. If you believe in the "calories in, calories out" rule of weight management, it should make no difference on body weight.
Shukla, for one, thinks that's oversimplifying things—or flat-out wrong in regards to this population. "In our previous study in patients with Type 2 diabetes, we showed that the carb-last meal order also influences gut hormones involved in regulation of satiety. GLP-1 is higher and ghrelin is suppressed for longer. Also, glucose dips stimulate hunger and so it is likely that glucose stability with sequential nutrient ingestion will help regulate hunger and satiety and impact weight gain."
She plans to test this in a prospective study in patients with prediabetes.
The Bottom Line
If you're among the 100-million- U.S. adults with prediabetes or Type 2 diabetes, starting a meal with fiber and fat, and saving the carbs for the end, is a simple strategy to reduce post-meal glucose spikes.
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