You may have heard the buzz that intermittent fasting can help you lose weight easily and live longer. At the same time, you may also be questioning the validity of fasting for aging well and whether to try fasting yourself. 

To help you decide whether intermittent fasting is for you, we did a deep dive into the literature (and there’s a lot). More research will be published on this hot topic, so our views may evolve as we learn more. 

Why the interest in intermittent fasting? Healthcare has extended length of lives, but not necessarily health and quality of years. The decline in health experienced with aging is influenced by biological and metabolic changes (such as blood sugar, insulin, waist circumference, lean body mass, blood pressure, cholesterol, and triglycerides) that occur during aging. The scientific interest in exploring whether intermittent fasting can improve how we age is increasing. And, if you’re like us, your interest is piqued because you want to age well while living longer. 

Some studies have shown that calorie restriction and increased exercise improved healthspan and delayed the onset of aging-associated declines. Intermittent fasting has been shown to stimulate similar biological pathways at a cellular level as caloric restriction and has emerged as a potential regimen for preventing or reducing the risk for certain diseases such as heart disease, cancer, neurodegenerative diseases, and obesity, as well as for improving brain function and mental clarity.

Types of Intermittent Fasting

Let’s start by defining the types of fasting being studied and discussed in the literature and online. 

• Alternate day fasting is eating a normal diet one day and fasting completely or moderately (consuming ~25% of daily calories or approximately 500-800 calories, called moderate alternate day fasting) the next.

• Fasting on some days of the week. The most popular application is called a 5:2 approach—where a normal diet is consumed for five days, and a fast is done for two days each week. The fasting days tend to be limited to approximately 25% of energy needs (500-800 calories).

• Time-restricted eating limits eating time to 4 to 12 hours during the day. 

• A fasting-mimicking diet is a period of a water-only or very low-calorie diet for two or more days separated from the next cycle by one week or longer. It was developed to be used in periodic cycles.

Research To Date 

It’s important to acknowledge that relatively few studies have explored the different intermittent fasting routines in middle-aged and older adults, and many of these studies were less than one year in length. More long-term research is needed to confirm the promoted health benefits for midlife adults. 

With that said, when reviewing studies conducted with broader populations, some have suggested that fasting regimens can aid in mild to moderate weight loss through consistent reductions in energy intake. However, recent literature reviews have not seen a significant difference over simply reducing calories throughout the day to control weight loss, glucose, and blood lipids. Reducing calories throughout the day or trying intermittent fasting can be viable options for reducing intake. Choose the approach that is easier to adhere to long-term, some people have found intermittent fasting easier than daily monitoring of caloric intake. With either approach, losing weight can improve health, especially in individuals who are overweight or obese.

Time-restricted eating has emerged as an eating approach that may support circadian rhythms. Most studies to date have been done in mice and supported by largely observational studies in humans, but they have shown benefits such as a reduction in fat mass, increased lean mass, reduction of inflammation, improved heart function, and improved natural body repair processes. 

Research done with rodents has also suggested that the health benefits of restricting eating windows without restricting calories were similar to the benefits of calorie restriction.  A few studies have shown that eating the same number of calories earlier in the day compared to late at night aids in weight loss without differences in caloric intake, macronutrient distribution, or energy expenditure furthering the interest in whether intermittent fasting, especially time-restricted eating, could be a practical approach for weight loss. It also has been proposed that time-restricted eating may increase metabolic flexibility enabling the body to fluctuate between burning carbohydrates and fat more easily. 

Metabolism may function more optimally in the morning, which suggests that eating earlier in the day may produce better weight outcomes.  Eating at night (between 5 pm and midnight) can often lead to eating too many calories, which can increase markers of inflammation. More research is needed to understand eating times, fasting periods, and health outcomes. Shorter eating windows (e.g., 12 hours) or consistent first and last meal times may be practical approaches for midlife women to use to control calorie intake without negatively impacting eating in social settings. 

Although some people find fasting difficult to adhere to long-term, others find intermittent fasting approaches easier to follow, making adoption and adherence to these approaches easier. Most people don’t have to overhaul their eating, avoid certain food groups, or monitor calories to follow a fasting approach, especially when doing time-restrictive eating. However, more research is needed to understand hunger, satiety, and long-term success with any fasting regimen. 

While intermittent fasting regimens appear to be safe for short periods, more research on humans is needed to assess safety for long-term use,  Most research has been done on people who are overweight or obese. More research needs to be conducted to determine whether fasting is safe for people at a healthy weight. 

In our experience, with any type of restrictive rule-based eating plan, women may miss out on important nutrients in their diets when they restrict food to a small eating window or fast on alternate days. As we age, getting the nutrients needed to maintain muscle mass and stay nourished can be more difficult, and adding a fasting regimen may make that even more challenging. 

When energy and nutrients are restricted, women may experience symptoms such as hunger, temperature changes, fatigue, headache, low energy, irritability, and gastrointestinal issues. Eating healthfully during any restricted eating plan is important to maintain energy, support mental health, and optimize healthspan. 

We’d love to say intermittent fasting is a key to aging well. Some studies done with lab animals show promising results, but the studies with humans are sparse, short-term, and therefore not yet conclusive. Plus, there’s a lack of consistency regarding an ideal regimen. 

Bottom Line

If you’re interested in trying intermittent fasting,  a shorter eating window (~12 hours) or consistent first and last meal times may be practical places to start for most healthy midlife women as we all wait for more evidence.

Small calorie reductions can be fine, but it’s important to get the nutrients, especially protein, you need to feel great, have the energy to participate in the activities you enjoy, and eat from all food groups. Being too restrictive can prove detrimental to aging well, especially if you lose lean body mass or you fall into an overly  “restrictive” eating pattern that impacts your joy of eating or your ability to eat with family or friends. 

Lastly, work with your healthcare provider if you have a chronic disease or are on any medications to ensure your chosen approach will work for you and not be counterproductive to your current medical regimen.