When intermittent fasting (IF) was first proposed as a dietary approach, many nutritionists said any weight loss would likely arise from the reduction in calories that inevitably occurs when you limit the amount of time during the day and night when you are eating. But studies since have begun to show that additional factors may be involved as well, making IF an intriguing approach to weight loss.
Intermittent fasting is an umbrella term for a variety of dietary schedules, all of which involve eating regularly some of the time and restricting calories in others. The method forms the cornerstone of a new weight-loss diet directed at menopausal women known as the Galveston diet.
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Some women in this age group put on weight around the abdomen that can be hard to dislodge, menopause experts say. So it’s not surprising that midlife women are especially interested in a dietary approach directed at them.
But the decision about whether IF is right for women over 40 needs to take into account a number of factors.
What Are the Types of Intermittent Fasting?
There are many different approaches to IF. Some people pick one to three days during the week when they eat minimally, if at all. Another technique, known as a fasting mimicking diet, severely restricts calories for five days in a month.
One of the more common IF approaches recommended for weight loss involves what is called 5:2 fasting, where you eat normally for five days in a week but seriously restrict calories, down to around 500 a day for women (600 for men), for any of the remaining two.
Other people use a time restricted eating (TRE) process, eating normally during any 8 to 12 consecutive hours in a day and fasting for the remaining hours. A TRE plan prohibiting food during a 16-hour window, known as 16/8, is what the Galveston diet recommends for midlife women.
Certain liquids are always allowed — indeed are encouraged — during fasting hours when little to no food is consumed. These include black coffee, teas (especially herbal tea), and water.
What Are the Weight Loss and Health Claims of Intermittent Fasting?
The Galveston diet touts IF as a whole-health panacea in addition to a weight loss tool. According to the website, IF prevents obesity, lowers heart risks, improves insulin resistance, decreases chronic inflammation, and boosts memory, mood, and energy.
The website claims that many of these proposed benefits come because IF brings about a process known as “metabolic switching,” when the body stops consuming its normal glucose for fuel and burns fat from storage instead.
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Over the years, people have attributed other benefits to intermittent fasting, everything from cholesterol and blood pressure reductions to taming Alzheimer’s disease and even boosting longevity.
Does the Evidence Show Intermittent Fasting Helps Midlife Women Lose Weight?
One of the largest and most recent reviews of the research on intermittent fasting in adults (both men and women), published in JAMA Network Open in December 2021, showed that some types of intermittent fasting do seem to help with moderate weight loss, with a moderate to high quality of evidence.
To reach this conclusion, the researchers evaluated 11 published meta-analyses, which cumulatively analyzed 130 separate randomized controlled trials.
Digging deeper into the analysis, the researchers found that only the 5:2 or a similar modified alternate-day fast was associated with “a statistically significant weight loss of more than 5 percent in adults with overweight or obesity.” They did not find that time-restricted eating, like the kind used in the Galveston diet, yielded similar results.
Additionally, the researchers note that IF seemed to be most successful during the first one to six months, after which people often experienced a weight plateau.
Intermittent Fasting May Lead to Similar Results as a Calorie-Restricted Diet, Preliminary Research Says
Another review, published in October 2021 in Annual Review of Nutrition did find that TRE, as well as alternate-day fasting and 5:2 eating, all led to weight loss, which they said was mild to moderate (1 to 8 percent lower than baseline weight). The researchers, from the University of Illinois at Chicago, observed that IF seems to result in the same amount of weight loss as the more traditional calorie-restriction diet that trims roughly 500 calories a day.
Most of the current research on intermittent fasting evaluated only a small number of people and didn’t follow them for long, says Ellen Liskov, RDN, a dietitian at Yale New Haven Hospital Center for Nutrition and Wellness in Connecticut. “These studies are not conclusive enough to say that intermittent fasting is a dietary plan that all people should employ,” she says.
Might Intermittent Fasting Help Women’s Heart Health?
Both review articles found evidence that intermittent fasting offers improvements related to heart health, an important area for midlife women since heart disease risk rises during this time.
The JAMA Network Open writers found several studies where adults on IF diets improved their low-density lipoprotein (LDL) cholesterol, total cholesterol, triglycerides, blood sugar, fasting insulin, insulin resistance, and blood pressure.
Many of these benefits occurred in people who were overweight or obese.
Similarly, the Annual Review of Nutrition analysis documented decreases in blood pressure and insulin resistance in some, as well as LDL cholesterol and triglyceride levels.
Is Intermittent Fasting Safe for Midlife Women?
“Intermittent fasting is generally safe and does not result in energy level disturbances or increased disordered eating behaviors,” the University of Illinois reviewers concluded.
Still, not every midlife woman should try this eating plan, they said. Those with a history of disordered eating, a body mass index (BMI) below 18.5, or those who need to take medication with food at regimented times should refrain.
Other experts say people with certain medical conditions may be poor candidates. Women with Crohn’s disease, for example, might do better on a different eating plan. And those with diabetes are also typically advised to refrain, especially when blood sugar isn’t well controlled.
What’s the Bottom Line for Midlife Women and Intermittent Fasting?
Liskov says she favors a time-restricted eating plan known as 12/12, where food is eaten for half the day, generally between 7 a.m. and 7 p.m. “This pattern of eating has helped many people lower their energy intakes, lose weight, and reduce the amount of unhealthy nutrients eaten,” she says. A key reason is that many people eat healthy foods during the day but then devolve to snacks of sweets and chips before bedtime.
It’s important to be sure you’re eating healthy foods during the eating window, rather than filling up on nutritionally empty calories, says Carol Roberts, MD, a functional medicine physician in Naples, Florida, who recommends IF to some of her patients. “If you’re on a junk food diet, it’s not going to be good for you to eat for fewer hours. Better food selection is also important,” she says.
To work long-term, an IF eating plan also has to mesh with your lifestyle, experts say. If you regularly go out socially for breakfast or eat dinner late at night, for example, aiming to fast during these times is not sustainable.
Mary Claire Haver, MD, the obstetrician-gynecologist who created the Galveston diet, suggests women who want to try IF ease into it, such as by pushing the morning meal back every few days until it’s finally close to noon.
Dr. Roberts says mornings aren’t the hardest part for most IF dieters aiming for a 16/8 schedule. “A cup of black coffee goes a long way toward keeping people happy in the morning. The hardest part for many is to not snack at night,” she says.
If you have a medical condition, it’s important to check with your physician before beginning any IF diet. And if you’re unsure about how to implement it in a healthy way, arrange for a consultation with a dietitian.
For women who are healthy or who have gotten the all-clear, there seems to be little downside in giving IF a try. You might finally drop some of those stubborn midlife pounds that haven’t otherwise budged.