Q: If I overeat or drink too much during the weekend, should I fast on Monday?
A: It can be tempting to cut excess calories after overindulging for a few days, however if you have diabetes you need to proceed with caution. Dramatically cutting down on your food consumption— if not carefully planned—can increase your risk of hypoglycemia especially if you are taking medications to lower blood sugar or are on insulin.
However, including a few low calorie days each week into your meal plan is not necessarily a bad thing. In fact, research1 has found that intermittent fasting may successfully reduce insulin resistance, blood glucose levels, and body weight .
So what is intermittent fasting? Essentially, it is a style of eating where you cycle between periods of eating followed by periods of fasting. Many styles of intermittent fasting exist from eating for only a few set hours each day, to fasting completely with no calories for a full 24-hour period, to an alternative style of eating where you rotate a normal days calories followed by a day of a significant reduction in calories.
Although each style of fasting may offer health benefits, if you have diabetes you need to be quite cautious about the type of intermittent fasting you choose. The rotation style of intermittent fasting, where you alternate days of normal calorie intake with days of significantly reduced calorie intake, to be quite effective at reducing insulin resistance and blood glucose levels.2 This may also be the safest method of intermittent fasting for individuals with diabetes, as complete fasting for long periods of time or a full 24-hour period can increase the risk of hypoglycemia and make medication management with diabetes a challenge.
A rotational style of intermittent fasting, such as the style outlined in my book, 2 Day Diabetes Diet, involves consuming a very low calorie diet two days per week while eating normally the rest of the week. When following such a plan, you must be cautious to adhere to certain guidelines to ensure your blood glucose levels stay within a healthy range. First, you should plan your fasting days to be on non-consecutive days whenever possible.
It’s also important to remember that even when you are ‘fasting,’ by consuming a very low calorie diet (approximately 600 calories per day), you should be making sure to eat every three to four hours to prevent excessive hunger or erratic blood glucose levels. And lastly, remember that ‘fasting’ isn’t just about reducing your overall calories. When you have diabetes, you must make sure your fasting days are still balanced in nutrient intake. This means incorporating all food groups to take in a balanced amount of carbohydrate, protein, and fat even in the presence of a reduced calorie meal plan.
Intermittent fasting is not for everyone. Individuals with type 1 diabetes or those with type 2 diabetes on insulin should receive clearance from their physician before attempting such a meal plan and should be followed closely by an experienced healthcare professional, such as a registered dietitian.
If you are very active and exercise intensely for more than one hour per day, you may find intermittent fasting does not provide you with the energy you need to sustain your activity on fasting days. If this is the case, plan to fast only on days where you are exercising more moderately or for a shorter length of time. For athletes, intermittent fasting is not recommended unless you are working alongside an experience dietitian who can help ensure your performance does not suffer on fasting days.
Although there are many ways to reduce body weight, lower insulin resistance, and manage diabetes, the research on intermittent fasting looks promising. One study looked at a diet that was much stricter on two days of the week but allowed for larger portions the rest of the week. Then researchers compared that approach to the typical diet that restricted calories 24-7.
Their findings are as counterintuitive as they are exciting: Women who followed the calorie-restricted diet for two days a week, but who consumed larger portions the rest of the week lost twice as much weight and reduced insulin resistance by 22% compared to dieters who restricted their eating all week long. Additional work by other research teams has confirmed those findings and even suggests more health benefits, including protecting your brain against some of the effects of Alzheimer’s and Parkinson’s disease3.
If you think intermittent fasting might help you reach your health and weight goals, be sure to enlist the help of your healthcare team. With some planning and consistency this method of eating just might be right for you.