Intermittent Fasting for Women Over 40: A Complete Guide

Losing weight after 40 is not easy! Weight loss is challenging because of hormonal changes, shifts in body composition, life responsibilities, and daily stressors.

Whether you’re in your 40s, your 50s, or beyond, perimenopause and menopause change how your body responds to food and weight loss. This guide covers intermittent fasting for all of those years.

Intermittent fasting, also known as IF, is a good option for women over 40 who want to lose weight without counting calories or restricting entire food groups. It has very few rules, which makes it a straightforward plan.

Because intermittent fasting limits how long you eat, it can make meal planning more manageable and reduce your total calorie intake.

Intermittent fasting may help you lose fat while keeping your muscle, especially when you eat enough protein and do strength training. That matters for women in this stage of life, when muscle loss speeds up. It also offers several health benefits and can reduce the risk of some common chronic diseases.

Intermittent fasting comes in different forms, such as the 16:8 and 5:2 plans. Some patterns are easier to follow in the short and long term. This post walks you through the different types of intermittent fasting.

What is Intermittent Fasting?

Intermittent fasting, or IF, is an eating style that alternates between periods of fasting and periods of eating. The goal is to abstain from eating for periods of 12 to 24 hours. 

Remember that intermittent fasting is not a diet plan. It only changes your eating habits by limiting when you can eat, not what you can eat. 

For example, if you follow the 16:8 IF pattern, you eat all your food for the day during a consecutive 8-hour period, and you fast for the remaining 16 hours. For instance, if your first meal starts at noon, you will finish your last meal by 8:00 pm. 

Intermittent fasting works because it can naturally cut your calorie intake. It also prolongs the time your body uses body fat for fuel, making it a good way to lose fat while conserving lean muscle. A study has shown that this healthy weight loss through IF can also increase your levels of human growth hormone, further encouraging muscle maintenance.

Can Intermittent Fasting Help with Weight Loss?

Several studies suggest that intermittent fasting can help with weight loss. For example, a 2020 review of 27 studies found weight loss between 0.8% and 13% of the initial weight.

However, more studies are necessary to say with certainty that IF helps with weight loss. More studies are needed to determine how intermittent fasting helps maintain weight loss in the long term.

Other Benefits of Intermittent Fasting for Women Over 40

Intermittent fasting can help control blood glucose in people with type 2 diabetes, a common problem for women over 40. A 2022 review of people with metabolic syndrome found that intermittent fasting led to small improvements in fasting blood sugar, hemoglobin A1C, and insulin resistance. 

This matters even more in menopause. As estrogen drops, your cells respond less well to insulin, which can lead to insulin resistance. Insulin resistance raises blood sugar and makes weight loss harder, so improving it can make weight management easier.

However, patterns that include fasting every other day, like the alternate-day fasting pattern, can have a negative impact. Studies indicate that fasting every other day might impair the action of the sugar-regulating hormone insulin in both the short term and long term.

If you have diabetes, it’s especially important to consult with a healthcare professional before starting the IF plan. I also recommend fasting for no more than16 hours and adjusting any blood glucose medications according to your eating and fasting hours.

Intermittent fasting can also improve metabolic syndrome, reducing the risk of heart disease and diabetes. Metabolic syndrome refers to a group of symptoms, including high blood pressure, high blood sugar, excess abdominal fat, and abnormal blood fat levels. 

Finally, intermittent fasting can also reduce inflammation and boost brain health.

Types of Intermittent Fasting for Women Over 40

Plan	Overview	Eating window	Fast days per week	Example
Time-restricted eating	Eat during a specific amount of time each day	1 to 8 hours	7	16:8
Alternate-day fasting	Eat one day, fast the next, repeat	Anytime	3 to 4	The every other day diet
Whole-day fasting	Fast two days a week	Anytime	2	5:2

16:8 Intermittent Fasting

In this plan, you fast for 16 hours and eat within an 8-hour window every day. 

There’s no set fasting time, but many people skip breakfast and have their last meal around their usual dinner time. 

You can follow this type of intermittent fasting by skipping breakfast, having your first meal by 11 am or noon, and finishing your last meal by 7 or 8 pm. 

As it naturally follows the eating patterns of traditional American diets, it’s easy to follow, making it very popular. Furthermore,  coffee is allowed within the fasting period, so you can still have black coffee in the morning. 

However, this pattern is only a suggestion. The 16:8 fasting plan is flexible, so you can follow many different eating patterns within the 24-hour window to fit your schedule, habits, and preferences. The only rule is to follow the same pattern every day.

Getting Started with the 16:8 Plan

During the first week you could stop eating at 8 pm (leaving you with an 11:13 plan). The next week you could skip breakfast and have your first meal at 10:00 a. (a 14:10 plan), and the week after that you have your first meal at 12 noon and finish eating the last at 8  pm.

Start with shorter fasting periods to make the transition easier.

Tricks to Avoid Feeling Hungry

Surprisingly, fasting can make people feel less hungry over time. However, to avoid feeling hungry, the quality of your diet is critical. 

For example, sugary, high-carbohydrate foods cause insulin spikes that can make you hungry. On the other hand, a diet rich in lean protein, healthy fats, vegetables, fruits, and complex carbohydrates can help you feel satisfied longer because it positively affects hunger hormones. The fasting schedule itself may help, too. In a small study, eating within a 6-hour window earlier in the day lowered ghrelin, the hormone that makes you hungry, and kept hunger steadier.

Here are some specific tricks to manage hunger:

• Eat a healthy diet throughout the day
• Eat filling foods for dinner: lean protein, healthy fats, vegetables, and foods rich in fiber
• Limit added sugars and high-carbohydrate foods
• Eat plenty of non-starchy vegetables throughout the day
• Drink plenty of fluids
• Drink decaffeinated tea at night
• Pick a routine that keeps your mind off of eating

Whole-Day Fasting: The 5:2 Plan

This plan is a different type of fasting. First, the number refers to days, not hours. So in this plan, you eat for five days and fast for two. 

But let’s be clear: a whole day of fasting means very little food, not no food. The 5:2 pattern calls for eating about 500 calories on each fasting day for women.

Does the 5:2 diet work? Unfortunately, few studies back up the effectiveness of this type of intermittent fasting. However, studies on the 4:3 plan show promising results.

Getting Started on the 5:2 Plan

It’s pretty simple; this plan’s only requirement is that you consume about 500 calories on 2 days a week. For the rest of the days, you eat without restricting calories. The fasting days don’t need to be consecutive, and they don’t even need to be the same 2 days every week, although it can help to pick the same days each week to make it easier to follow.  

It’s more sustainable to eat two or three days, fast one day, and repeat, as long as you only fast two days each week.

For your general health and to avoid cravings, eat a well-balanced diet of vegetables, fruits, lean proteins, healthy fats, and whole grains, while avoiding sugars, high-carbohydrate meals, junk food, and excessive food during eating days. For successful weight loss, don’t overcompensate for fasting days by overeating on the other days. To lose weight, you will need to eat fewer calories overall throughout the week.

You might choose to eat 2-3 meals of very low-calorie foods on fasting days, totaling no more than 500 calories. If you avoid doing two consecutive days of fasting, it can make it easier to stick to the plan.

Food and Meal Ideas for the 5:2 Diet 

• Non-starchy vegetables such as leafy greens, lettuce, arugula, mushrooms, peppers, and onions. Avoid potatoes, malanga, yuca, butternut squash, sweet potato, corn, and anything else with starch. 
• Plain Greek yogurt and berries.
• Hard-boiled eggs.
• Small amounts of lean protein.
• Broths.
• Coffee, tea, water.

It’s astonishing how easy it is to eat only 500 calories! Here are some meal plans for your fasting days:

• 27 meal ideas 
• More meal ideas

A Dietitian’s Opinion on the 5:2 Plan

In my professional and personal opinion, this type of intermittent fasting can be challenging to maintain in practice, as it requires more planning than other types of IF. 

You will need to consider how you feel on fasting days and how well you can control your intake on non-fasting days so you don’t overeat. Also, be aware that certain medical conditions can make this plan unsafe.

Whole-Day Fasting: The 4:3 Plan

This plan is similar to the 5:2 plan, but you fast three days a week instead of two. Like the 5:2 program, the 4:3 plan has you eat 500 calories on fasting days. 

Benefits

• Improves insulin resistance
• Reduces markers of oxidative stress
• Decreases markers of inflammation (which can help with the prevention and treatment of many chronic diseases)
• Reduces body weight: in a 12-month study, people on the 4:3 plan lost about 6 pounds more than those who cut calories every day
• Less binge eating and out-of-control eating, compared with cutting calories every day
• Decreases fat mass without change in muscle mass

Food and Meal Ideas

• Non-starchy vegetables such as lettuce, arugula, mushrooms, peppers, and onions. Avoid potatoes, malanga, yuca, butternut squash, sweet potato, corn, and other starchy foods. 
• Plain Greek yogurt and berries.
• Hard-boiled eggs.
• Small amounts of lean protein.
• Broths.
• Coffee, tea, water.
• Meal ideas

Alternate-Day Fasting

This type of intermittent fasting is also known as the every-other-day fasting diet because, as the name suggests, it alternates between a day of fasting and a day of eating. 

As with the other plans, on the fasting days you can consume up to 500 calories. 

Some studies suggest that alternate-day fasting can help decrease obesity, markers of inflammation, heart disease and diabetes, and improve pulmonary function. However, research shows that the plan is not superior to traditional caloric restriction.

Possible Side Effects of Intermittent Fasting

In some studies, a small proportion of people who followed intermittent fasting reported the following side effects:

• Hunger and cravings
• Headaches and light-headedness
• Nausea, diarrhea, bloating
• Dehydration
• Irritability and other mood swings
• Fatigue
• Lower energy levels
• Weakness
• Low blood sugar
• Difficulty sleeping
• Malnutrition

Before You Begin Intermittent Fasting 

Before you start intermittent fasting, determine whether the plan is suitable and safe for you.

If you are diabetic and on medication designed to lower your blood sugar, the medicines need to be adjusted to match your eating schedule. As a doctor in clinical nutrition, I recommend avoiding whole-day fasting plans and talking to your doctor about adjusting your medication to match your eating and fasting times.

Also, speak to your health care provider if you take medications that must be taken with food.

Finally, the plan might not be suitable for you if:

• You regularly experience low blood sugar
• You have type 1 diabetes and use insulin
• You are underweight
• You have an eating disorder, or have had one in the past
• You are immunocompromised

Seek medical advice if you have any doubts about whether this plan is healthy for you.

Why is Intermittent Fasting Not Working for Me?

Although intermittent fasting (IF) has proven effective for many people, some may not see the results they hope for.

Eating Too Much During Eating Windows

Eating too much during non-fasting periods can negate IF’s benefits in several ways.

When you fast, your body undergoes several physical changes, including improved insulin sensitivity, increased fat burning, and reduced inflammation. However, if you consume too much food during non-fasting periods, it can have the following negative effects:

Calorie Surplus

Fasting often helps you eat fewer calories, which can lead to weight loss. But if you take in more calories than your body needs during the eating window, you will not lose the weight you are hoping for.

The Bottom Line

Intermittent fasting for women over 40 is an easy, effective way to lose weight, and it also offers potential health benefits. So it’s no surprise that intermittent fasting has become a popular method for losing weight and maintaining it. In my practice, I often see that when patients follow IF, they naturally cut the night snacks. For most people, eating well during the day is much easier than controlling cravings at night.

In my professional opinion, the 16:8 is more sustainable and easier to follow. It works because it’s flexible, intuitive, inexpensive, and sustainable.