Can Intermittent Fasting Help You Lose Weight?

clocks on a pink background representing intermittent fasting

For some of us, fasting for weight loss doesn’t sound fun. If you’ve ever been hangry (that is, the miserable combination of hungry and angry), you get it. So it’s no surprise that many women give intermittent fasting the side-eye. But research shows that there are likely benefits for people looking to lose weight or prevent diabetes. 

What is intermittent fasting?

When we eat, our bodies break down food and, with the help of insulin, convert it into sugar that provides the energy cells need to function. Anything cells don’t use gets stored as fat. Insulin is responsible for keeping sugar in fat cells. We lose weight only when insulin levels go down, allowing us to burn fat for fuel instead of sugar. This happens in between meals, when we are not eating.

The idea of intermittent fasting is to abstain from eating long enough for the body two switch from burning sugar to burning fat. Intermittent fasting can be as simple as avoiding food later in the day and at night, creating a 12- to 18-hour window when you’re simply not consuming calories (also known as circadian-rhythm fasting). 

A 2018 study found that participants who ate only between 7 a.m. and 3 p.m. had improved insulin sensitivity, lower blood pressure, and decreased appetite. 

In December 2019, The New England Journal of Medicine published a study that found that “evidence is accumulating that eating in a six-hour period and fasting for 18 hours can trigger a metabolic switch from glucose-based to ketone-based energy, with increased stress resistance, increased longevity, and a decreased incidence of diseases, including cancer and obesity.”

That study, titled “Effects of Intermittent Fasting on Health, Aging, and Disease,” found that the long-term adaptive responses to intermittent fasting may include:

  • Increased insulin sensitivity 
  • Increased heart rate variability (a measure of stress response)
  • Improved lipid metabolism 
  • Healthy gut microbiota
  • Reduced abdominal fat (of concern to many menopausal women)
  • Reduced inflammation 
  • Reduced blood pressure
  • Greater resilience
  • Disease resistance

Should you try it?

Research so far indicates that intermittent fasting has promise for the treatment of obesity. 

“There is some good scientific evidence suggesting that circadian-rhythm fasting, when combined with a healthy diet and lifestyle, can be a particularly effective approach to weight loss, especially for people at risk for diabetes,” says Dr. Monique Tello, a physician at Massachusetts General Hospital and clinical instructor at Harvard Medical School. 

To date, however, human studies have been small and short in duration. (Most of the research on intermittent fasting has been done with male mice, according to The Cooper Institute.) More research is needed to make an evidence-based case for or against. 

For sure intermittent fasting it isn’t for everyone. Women with advanced diabetes, heart disease, or a history of eating disorders, and those who are pregnant or breastfeeding should not try intermittent fasting. 

But if you’re looking to slim down and you’re otherwise healthy, you might try it and keep tabs on how you feel. However, as always, check with your doctor before making any major dietary changes.

Get started

If you’re new to intermittent fasting, take it slow. Some people start with a 12-hour window: finish dinner by 7 p.m. and hold off on breakfast until 7 a.m. Others start aiming for 16 calorie-free hours, or finishing dinner by 8 p.m. and not eating again until noon the next day. Some people fast on alternate days. Others do it every day. And it’s important to note that during nonfasting hours, intermittent fasters are not restricting calories. They eat healthfully until they are satisfied.

Whatever way you go, stay hydrated. Some nutritionists recommend that women who are trying to lose weight aim to drink half their body weight in ounces of water each day (for example, if you weigh 140 pounds, try to drink 70 ounces of water per day). There’s no science behind that recommendation, but it’s not a bad goal, especially during the summer or if you exercise a lot.

Some experts encourage pairing intermittent fasting with a plant-based or Mediterranean-style diet. Finally, if you’re trying intermittent fasting for weight loss, know that it can take several weeks to see results.

Curious about other diets that help older women lose weight and stay healthy? Read 5 Popular Diets for Women Over 40.

Photo: Eleonora Grigorjeva

About the author
Kristen is a Brooklyn-based writer and marketing professional who loves to run.

Filed under: Nutrition, Your Body