Intermittent Fasting for Diabetes Weight Loss: Not So Fast

Health Writer

Intermittent fasting is continuing to gain in popularity as a diet trend credited with assisting in weight loss, possibly improved cardio-metabolic health, reducing the risk of diabetes, and even helping to simplify eating for those individuals who struggle with a defined and consistent meal plan. There have been animal and human studies on the impact of intermittent fasting that have confirmed the benefits (reduced inflammation, preserved cognitive function, protection against heart disease). A January 2018 study out of New Zealand showed some troubling problems that may confront individuals diagnosed with diabetes who try intermittent fasting in order to lose weight.

Intermittent fasting typically involves “fasting for 24 hours” two days a week (5:2). On the fast days you can have certain fluids and in some cases very minimal food. The body’s response to this program is to convert certain types of fat into fatty acids that the blood can absorb. This produces ketones which the body uses for energy. The net result is that the process appears to alter metabolism and may help to nudge weight loss with less stress on the body, meaning less inflammation. There have been some previously documented negative associations with this type of diet program.

The study focused on a specific health scenario to see how intermittent fasting would affect unique health parameters. The New Zealand researchers gathered 41 adults with type 2 diabetes. All subjects had a BMI that fell between 30 and 45, and baseline HbA1c levels ranged between 6.7 and 10 percent. All participants were taking metformin or other hypoglycemic medications. The subjects were instructed to either fast for two consecutive or non-consecutive days for a 12 week period. On fasting days, medication levels were reduced.

Primary outcomes that were evaluated were their “rates of hypoglycemia,” unpleasant blood sugar drops. Secondary outcomes that were evaluated included weight, glucose and HbA1c levels, liver function and change in diet. Thirty seven out of the forty one patients were included in the findings:

  • Among 15 patients, 52 hypoglycemic events occurred during 84 days of observation
  • During fasting days, the risk of having hypoglycemia nearly doubled
  • Despite reduction of medications, fasting of any kind increased the rate of hypoglycemia events
  • These hypoglycemia events occurred in both groups – the consecutive and non-consecutive days fasting approach
  • Both groups showed similar weight loss, improvements in HbA1c, and small improvements in quality-of-life.

Despite the clear benefits that intermittent fasting provided, it’s clear that periods of hypoglycemia are serious in nature. In fact, three endocrine experts reviewed this study and published a joint statement on EndocrineWeb suggesting that other dietary approaches to weight loss and improvement in blood glucose goals are “less hazardous and just as or more effective” than intermittent fasting. In fact, a standard very low calorie diet that allows eating daily typically offers a greater weight loss (more than the six to seven pounds lost in the New Zealand study over 12 weeks) with lower rates of hypoglycemia. If intermittent fasting is the desired approach for some patients, then the endocrine experts strongly recommended working closely with their medical team to constantly guard for hypoglycemia and to adjust medications to help to avoid that risk.

The endocrine experts suggest that the best and most consistent way to lose weight and keep it off, when you are dealing with a diagnosis of obesity and diabetes is to limit carbs in your diet. Eating less than 150 grams of starchy carbohydrates daily improves blood sugar levels and helps to promote weight loss for most people with Type 2 diabetes. Quality of carbs – choosing high fiber, less starchy – is also quite important.

One of the endocrine experts also suggested that most people are not able to sustain intermittent fasting for a significant period, and that typically means a period of weight gain, often more than was lost, once you abandon the fasting program. So despite the benefits that the diet program seems to offer, the downside of periods of hypoglycemia needs to be strongly considered in people diagnosed with diabetes.

If you do want to target the carbohydrate goal of less than 150 grams daily, then consider emphasizing these non-starchy carbohydrates in your daily diet:

  • Amaranth or Chinese spinach
  • Artichoke
  • Artichoke hearts
  • Asparagus
  • Baby corn
  • Bamboo shoots
  • Beans (green, wax, Italian)
  • Bean sprouts
  • Beets
  • Brussels sprouts
  • Broccoli
  • Cabbage (green, bok choy, Chinese)
  • Carrots
  • Cauliflower
  • Celery
  • Chayote
  • Coleslaw (packaged, no dressing)
  • Cucumber
  • Daikon
  • Eggplant
  • Greens (collard, kale, mustard, turnip)
  • Hearts of palm
  • Jicama
  • Kohlrabi
  • Leeks
  • Mushrooms
  • Okra
  • Onions
  • Pea pods
  • Peppers
  • Radishes
  • Rutabaga
  • Salad greens (chicory, endive, escarole, lettuce, romaine, spinach, arugula, radicchio, watercress)
  • Sprouts
  • Squash (cushaw, summer, crookneck, spaghetti, zucchini)
  • Sugar snap peas
  • Swiss chard
  • Tomato
  • Turnips
  • Water chestnuts
  • Yard-long beans

See more helpful articles:

Fasting: Why These Diets Are Getting So Much Attention

Types of Fasting Diets

10 Superfoods for Type 2 Diabetes