Study Finds Alternate-Day Fasting Improves Fasting Insulin and Insulin Resistance

A study observed that alternate-day fasting leads to greater reductions in fasting insulin and insulin resistance compared with calorie restriction in patients with insulin resistance.

Researchers compared the effects of the two eating patterns in overweight and obese adults with insulin resistance. A secondary analysis included 43 patients who participated in a 12-month study that compared the two eating patterns with a control group. Alternate-day fasting was defined as consuming 25% of energy needs on a fast day and consuming 125% of energy needs on alternating “feast days.” Calorie restriction was defined as consuming 75% of energy needs every day.

Weight loss did not differ between the two cohorts: By month 12 in the alternate-day fasting group, participants lost a mean of –8% (standard deviation [SD], 2%), while the calorie restriction cohort lost a mean of –6% (SD, 1%) relative to the control group (P<0.0001).

Compared with calorie restriction, alternate-day fasting resulted in greater decreases (P<0.05) in fasting insulin (–52% [SD, 9%] versus –14% [SD,9%]) and insulin resistance (–53% [SD, 9%] versus –17% [SD, 11%]). Alternate-day fasting also produced similar results compared with the control group.

However, the following factors remained unchanged with alternate-day fasting:

  • Lean mass
  • Visceral fat mass
  • Low-density lipoprotein cholesterol
  • High-density lipoprotein cholesterol
  • Triglycerides
  • Blood pressure
  • C-reactive protein
  • Tumor necrosis factor α
  • Interleukin-6 values

“These findings suggest that alternate-day fasting may produce greater reductions in fasting insulin and insulin resistance compared with calorie restriction in insulin‐resistant participants, despite similar decreases in body weight,” the researchers concluded. Read more

The results of the findings were published in Obesity.