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Fasting to Reduce the Risk of Diabetes

Research suggests intermittent fasting to reduce the risk of diabetes could help lower cholesterol and help with weight loss.

Public health officials concerned about the epidemic of diabetes and pre-diabetes have focused on weight loss through exercise and healthy eating. Increasingly, evidence suggests that intermittent fasting may be a useful tool.

Studying 5:2 Intermittent Fasting to Reduce the Risk of Diabetes:

Intermittent fasting has been hailed as a potential therapy for type 2 diabetes, but doctors rarely prescribe it. A new study from China published in JAMA Network Open shows how effective this approach can be.

The scientists recruited about 400 individuals who had been recently diagnosed with type 2 diabetes (JAMA Network Open, June 21, 2024). They allocated these participants randomly into one of three groups for a four-month trial followed by two months of follow-up data collection. The primary outcome was HbA1c, a measure of blood glucose over time.

One group took the diabetes drug metformin. A second group took empagliflozin (Jardiance). The third group fasted for two nonconsecutive days each week, reducing their intake to just one-fourth of their usual calories by using meal replacements on those days. The meal replacements provided 500 calories for women and 600 calories for men. 332 volunteers completed the study, designated the EARLY trial.

According to the investigators, people in the 5:2 intermittent fasting group reduced their HbA1c the most, with a significant advantage over those in the metformin and empagliflozin groups. 80% got their HbA1c down below 6.5%, whereas 60% of those on metformin and 55% of those on empagliflozin did that well. The researchers suggest that intermittent fasting could be an effective lifestyle intervention for early-stage type 2 diabetes.

How Could Intermittent Fasting Help?

There have been several studies of alternate-day fasting as a way of achieving weight loss or blood sugar control (Metabolism, Jan., 2013; Nutrition Journal, Nov. 12, 2013; American Journal of Clinical Nutrition, Nov., 2009). In most of these studies, people eat dramatically less (but still something) on the fast day. The body’s adaptation to fasting seems to be beneficial in many respects.

Water-Only Fasting:

A previous study suggested that routine water-only fasting one day a week can pull cholesterol out of the fat cells. Researchers at the Intermountain Heart Institute had observed that people who regularly fasted had a lower risk of diabetes and heart disease. As a result, they enrolled healthy subjects and people with prediabetes and metabolic syndrome in this clinical trial.

During the 24 hours of the zero-calorie fast, blood cholesterol levels rose. But with periodic water-only fasting once weekly over six weeks, cholesterol levels actually fell slightly. The individuals with pre-diabetes also lowered their insulin resistance. The study volunteers included both obese and normal-weight people. They lost an average of three pounds during the study.

Update:

The scientists presented their findings at the American Diabetes Association Scientific Sessions, in San Francisco on June 14, 2014. We did not find a publication within a few years of their presentation as we expected.

Instead, they published a comprehensive review trying to determine whether therapeutic fasting regimens have clinical benefits for patients (American Journal of Clinical Nutrition, Aug., 2015). They concluded that more high-quality research is needed before fasting (intermittent or otherwise) can be recommended as a health intervention.

Last year, however, they published the results of the WONDERFUL trial, which seem to follow the protocol described above with once a week water-based fasting (International Journal of Cardiology. Cardiovascular Risk and Prevention, Sep. 11, 2023). This analysis describes a short-term increase in the risk of mortality, followed by reduced risk over the longer term.

The People’s Pharmacy Perspective:

Intermittent fasting sounds like an interesting tactic to lower cholesterol and reduce the risk of progressing from pre-diabetes to diabetes. Other scientists have shown that intermittent energy restriction changes insulin responses and the way the body handles lipids following a meal (British Journal of Nutrition, March 28, 2016). This might explain the results that the Utah researchers found.

If you think about human evolution, it makes sense that periodic fasting would be tolerable if not actually beneficial. Over the course of millennia, our forebears often encountered periods when they would have little or nothing to eat for a day or two.

Learn More:

In pre-diabetes, blood sugar is elevated, but still falls below the cut-off for a diagnosis of diabetes. We discuss other ways to ward off diabetes or reduce the likelihood of complications in our Guide to Managing Diabetes. You will also find a number of methods to reduce blood fats in our Guide to Cholesterol Control and Heart Health.

You may also wish to listen to Show 1143: Can You Control Your Blood Sugar by Fasting? Time-restricted eating is another version of intermittent fasting to reduce the risk of type 2 diabetes. To learn more about that approach, you might listen to Show 1094: Does It Matter When You Eat?

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
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Citations
  • Guo L et al, "A 5:2 Intermittent Fasting Meal Replacement Diet and Glycemic Control for Adults With Diabetes: The EARLY Randomized Clinical Trial." JAMA Network Open, June 21, 2024. DOI: 10.1001/jamanetworkopen.2024.16786
  • Klempel MC et al,, "Alternate day fasting (ADF) with a high-fat diet produces similar weight loss and cardio-protection as ADF with a low-fat diet." Metabolism, Jan., 2013. DOI: 10.1016/j.metabol.2012.07.002
  • Varady KA et al, "Alternate day fasting for weight loss in normal weight and overweight subjects: a randomized controlled trial." Nutrition Journal, Nov. 12, 2013. https://doi.org/10.1186/1475-2891-12-146
  • Varady KA et al, "Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and cardioprotection in obese adults." American Journal of Clinical Nutrition, Nov., 2009. DOI:https://doi.org/10.3945/ajcn.2009.28380
  • Horne BD et al, "Health effects of intermittent fasting: hormesis or harm? A systematic review." American Journal of Clinical Nutrition, Aug., 2015. DOI: 10.3945/ajcn.115.109553
  • Horne BD et al, "Intermittent fasting and changes in clinical risk scores: Secondary analysis of a randomized controlled trial." International Journal of Cardiology. Cardiovascular Risk and Prevention, Sep. 11, 2023. DOI: 10.1016/j.ijcrp.2023.200209
  • Antoni R et al, "Investigation into the acute effects of total and partial energy restriction on postprandial metabolism among overweight/obese participants." British Journal of Nutrition, March 28, 2016. DOI: 10.1017/S0007114515005346
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