For most people, there's no single healthy way to eat, though there are healthy foods and eating patterns. Yet for people with prediabetes, a low-carb diet could quickly bring elevated A1C levels back to a healthier range, a trial published in JAMA Network Opensuggests. But while this research revealed several benefits of low-carb eating to blood sugar control, Dr. Giulio Romeo, associate medical director of the Adult Diabetes Section at Harvard-affiliated Joslin Diabetes Center, wonders whether its rigorous approach is realistic in everyday life. "Clearly this study shows that a low-carb — and really, a borderline very-low-carb — diet is effective in reducing A1C levels, which are a measure of blood sugar during the previous three months," he says. "But it may or may not be sustainable in the long run." Prediabetes affects an estimated 96 million American adults. This condition is characterized by higher-than-normal-range blood sugar levels, and puts people at higher risk for developing full-blown diabetes. Which foods were study participants asked to eat — or avoid? This randomized clinical trial — considered the gold standard in scientific research — enrolled 150 older adults with untreated prediabetes or less severe diabetes. All were overweight (average BMI 35); nearly three-quarters were women and 59% were Black. Over the course of six months, half were randomly assigned to a low-carb diet and frequent dietary counseling, while the other half continued eating their usual diet. During the first three months, low-carb participants needed to keep carbohydrate levels below 40 grams a day — that's roughly the amount of carbs in an English muffin and an apple. During months four through six, their carb limit was below 60 grams a day. The researchers recommended that participants veer toward proteins and healthy fats by eating non-starchy vegetables, fish, poultry, lean meat, eggs, olive oil, avocados, nuts and seeds, Greek yogurt, low-carb milk, and small amounts of cheese. They were advised to limit or avoid other dairy, fruits, legumes, beans, and grains. The low-carb participants were provided various foods throughout the study, including olive oil, green beans, tomatoes, tuna, non-sugar sweetener, nuts, and low-carb bars and shakes.