Are you interested in trying intermittent fasting to help manage obesity? If you’re new to the idea of intermittent fasting or you’re still learning about it, you may not know whether it’s right for you.

Intermittent fasting is a type of eating pattern that may help some people living with obesity manage their weight, but there are limitations. Intermittent fasting is not recommended for anyone with a history of eating disorders, people with diabetes or a weakened immune system, or those who require regular meals to safely take their prescription medications.

Learn more about intermittent fasting with obesity, including common intermittent fasting plans, tips to get started, and the importance of talking to a doctor first.

What Is Intermittent Fasting?

Intermittent fasting means you only eat during certain times of the day, or you eat a very low-calorie diet (500 to 600 calories per day) or nothing at all on certain days each week.

Although intermittent fasting is all about when you eat, it’s also important to make sure you eat nutritious foods during times when you aren’t fasting. Meal prepping and easy recipes can offer convenience, but it’s also key to listen to your body and choose foods that nourish and satisfy you, without feeling restricted.

Benefits of Intermittent Fasting

Research has shown that intermittent fasting may have health benefits. However, most studies are short term, and more research is needed to understand its long-term effects and sustainability.

Potential benefits of intermittent fasting for obesity include:

• Weight loss
• Less risk of heart problems
• Reduced waist circumference

Intermittent fasting as part of an obesity treatment plan that also includes exercise and a healthy diet may lead to better outcomes, but more research is needed to know for sure.

Common Intermittent Fasting Plans

There are several types of intermittent fasting, and everyone’s nutrition needs and dietary habits are unique. Rather than focusing on calories alone, consider how your eating patterns can support your overall health, energy, and well-being. It’s a good idea to talk to your doctor or a registered dietitian about what approach may best suit your individual needs and lifestyle.

These are some common plans for intermittent fasting.

16:8 Plan

The 16:8 plan is one of the most common approaches to intermittent fasting. With the 16:8 plan, you only eat during an eight-hour period, such as from 10 a.m. to 6 p.m. each day. In that case, the fasting period would be from 6 p.m. until 10 a.m. the next day.

14:10 Plan

The 14:10 plan is similar to the 16:8 plan. It just has a longer, 10-hour eating window. These plans are called time-restricted eating plans. They can be easier to do since most people fast overnight anyway.

5:2 Plan

The 5:2 plan is also called twice-a-week fasting. With the 5:2 plan, you choose two days a week when you eat a very low-calorie diet. There must be at least one day of normal eating between fasting days. On your five nonfasting days, you eat the same amount of food you normally eat.

There are different versions of the 5:2 plan regarding fasting days. One version includes eating one meal that is between 500 and 600 calories on each fasting day. Another version is eating one 200 calorie meal and one 300 calorie meal on each fasting day.

Alternate-Day Fasting Plan

The alternate-day fasting plan is where you switch between normal eating days and modified fasting days every other day. It’s called modified fasting because you’re not completely fasting. Instead, on fasting days you eat 25 percent of the amount of calories you would eat on a normal day (around 500 calories for the average person).

Eat, Stop, Eat Plan

Following the eat, stop, eat plan means not consuming any calories for 24 hours. For example, you would stop eating after breakfast one day until breakfast the next day. Fasting days should only be one or two days a week. It’s important to eat your usual balanced diet on the other days of the week.

Tips To Get Started

It’s important to talk to your doctor and make a plan before you start intermittent fasting. Having a plan will help with fasting in a healthy way. It may take two to four weeks for your body to get used to an intermittent fasting plan.

Here are some tips to help you get started with intermittent fasting:

• Drink plenty of fluids to stay hydrated — Be sure to choose drinks without added sugar, such as water or herbal teas.
• Choose nutrient-rich foods — During nonfasting times, eat healthy foods including fruits, vegetables, whole grains, lean protein, and foods high in fiber to keep you full.
• Go slow — Slowly increase fasting time windows over a few days or weeks.
• Keep a record — Write down your fasting schedule, and keep track of how you feel and whether your body weight changes.
• Honor your body — Listen to your body to avoid extreme hunger, fatigue, and stress. Signs like irritability, low energy, or preoccupation with food may be indicators that fasting isn’t serving your well-being. Your body’s signals are valid.

If at any time you feel intermittent fasting doesn’t support your physical or mental well-being, that’s OK. Trust your body, and be kind to yourself. You can talk with a healthcare provider about how you’re feeling and explore other approaches that better support your health and lifestyle.

What MyObesityTeam Members Say About Intermittent Fasting

Several MyObesityTeam members have experience with intermittent fasting and share their advice.

One member shared they are doing intermittent fasting for weight management after losing some weight. “I eat between an eight-hour time span and nothing but water, tea, or coffee for 16 hours. … I had a late-night snacking problem which really added up the calories and found this helped with that,” they wrote.

In response to one member asking how to start a fast for the first time, another wrote, “I started out just a few hours drinking just water and juice. I am up to fasting from 6 a.m. when I wake up to 2 p.m. or 3 p.m. at the latest.”

Other members have noted that intermittent fasting isn’t for everyone and highlight the importance of talking with a doctor. “I am not healthy enough to do intermittent fasting, and doing it when your body isn’t ready can cause weight gain. So please consult a doctor, be careful, and listen to your body!” one member advised.

Who Shouldn’t Try Intermittent Fasting?

Intermittent fasting is generally not recommended for people who:

• Are pregnant or breastfeeding
• Have diabetes
• Have a history of an eating disorder or an unhealthy relationship with food
• Have low bone density
• Have a weakened immune system
• Take prescription medications that require food

Interactions With Certain Medicines

Talking to a doctor first is especially important if you have type 1 diabetes or take insulin. People who take insulin may not be able to fast because it could cause hypoglycemia (low blood sugar).

Fasting may also be risky for people who take medications that require food or affect fluid and mineral balance, such as those for heart conditions or high blood pressure. Without food, these medications may cause nausea, stomach irritation, or imbalances in sodium and potassium levels.

Always Talk With a Doctor Before Starting Intermittent Fasting

It’s important to talk to a healthcare provider or nutritionist before starting intermittent fasting to make sure it’s safe for you. A healthcare provider can also help you choose a plan that is best for you based on your overall health and health goals.

Possible Risks and Side Effects

Intermittent fasting may lead to unhealthy changes in the body. One study found that alternate-day fasting significantly increased LDL cholesterol (“bad” cholesterol) levels in people with obesity after one year. It also found that intermittent fasting did not produce more weight loss or cardiovascular benefits than following a daily low-calorie diet without fasting.

Another study found that people who only ate during a time window of eight hours or less had a higher risk of death from cardiovascular disease. This doesn’t mean that intermittent fasting caused death, and there could have been other factors at play. More research is needed to better understand the long-term effects of intermittent fasting.

Some intermittent fasting plans also have intense side effects that can make the plan hard to follow. For example, the eat, stop, eat plan can cause:

• Extreme tiredness or low energy
• Headaches
• Irritable mood
• Extreme hunger

Some side effects may be too much to take. It’s important to listen to your body’s signals. If you’re experiencing these side effects, talk to a doctor to make sure your intermittent fasting plan is safe and beneficial for you.

Talk With Others Who Understand

MyObesityTeam is the social network for people with obesity and their loved ones. On MyObesityTeam, more than 57,000 members come together to ask questions, give advice, and share their stories with others who understand life with obesity.

Have you tried intermittent fasting? How did it go? Share your experience in the comments below, or start a conversation by posting on your Activities page.