Intermittent fasting cuts calories and can help you manage, not cure your metabolic dysfunction-associated steatotic liver disease (MASLD). New research suggests that it’s not just what or how much you eat but when you eat.
Intermittent fasting is a pattern for eating based on time limits. And people with MASLD who use intermittent fasting appear to lose weight and lower the levels of fat in their liver.
A recent 12-week study found that almost three-quarters of people who did intermittent fasting were able to lower their liver fat by at least 30%. That means intermittent fasting helped them get rid of about a third of their liver fat.
“Intermittent fasting helps reduce fat around the liver because it produces weight loss,” says Kristina Varady, PhD, a professor of nutrition at the University of Illinois Chicago in Illinois, who also studies intermittent fasting.
Remember that intermittent fasting isn’t a cure for your MASLD, and the diet may not suit everyone. But some people may find it a useful way to help control the disease. Here’s what you should know about intermittent fasting, why it may help treat your MASLD, and how to do it safely.
What Is Intermittent Fasting?
Intermittent fasting is exactly what it sounds like — you rotate between periods of eating and fasting. It’s not about not eating, either.
You’ll scale back on calories for hours, not days. You can also drink water, black coffee, and tea while you fast.
There are a few ways to do intermittent fasting.
The 16/8 method (time-restricted eating)
You limit what you eat to a specific window of time each day, such as 4-10 hours. Most people opt to eat within an eight-hour window and fast for around 16 hours.
The eight-hour eating window is usually 6 AM to 3 PM each day. But you can also try a midday restriction window where you don’t eat from 11 AM to 8 PM. You choose what works best for your body.
Eat-stop-eat method
You eat a low-calorie, plant-based diet and avoid animal protein completely for many days each month. The eat fewer calories, stop animal protein, and eat again method can mimic fasting.
This can act like prolonged fasting, but it doesn’t completely restrict your calories. It’s an easier and safer way to stick to a fasting diet plan without completely cutting out all your calories.
On day 1, you usually eat 600 calories, and on days 2-5, you’ll eat 300 calories. You’ll eat normally the rest of the month. You’ll repeat this cycle every three to four weeks for up to eight cycles.
The 5:2 fasting method
Also known as short-term or periodic fasting, you don’t eat anything for two days a week. It’s the most popular fasting diet because you get to eat normally the rest of the week.
You choose whichever two days of the week you want, but there must be at least one non-fasting day between them.
Alternate-day fasting (ADF)
ADF is also called every-other-day fasting. You'll eat normally one day --- it's called your “feast day.” Then you’ll only eat 500-600 calories the next day, usually in the form of one meal. This is called your “fast day.”
What Are the Health Benefits for Intermittent Fasting?
Research shows that intermittent fasting can give you certain health benefits such as:
- Weight loss
- Lower heart disease risk
- Blood sugar control
- Lower inflammation
The main reason intermittent fasting helps with weight loss and lowers your “heart disease and diabetes risk is simply because you take in fewer calories,” says Maya Balakrishnan, MD, MPH, a liver specialist at the Baylor College of Medicine in Houston. “It may also help manage your blood glucose levels and reduce overall inflammation in your body, but we think most of the benefit is due to weight loss.”
Weight loss
Studies show that intermittent fasting may help you lose up to 10% of your total body weight if your BMI is 25 or more.
Lower heart disease risk
Intermittent fasting helps lower total cholesterol, LDL (bad) cholesterol, triglycerides, and your blood pressure. It may raise your HDL (good) cholesterol, too.
Better blood sugar control
Fasting seems to better stabilize blood glucose and insulin levels than simply following a low-calorie diet.
Less inflammation
Intermittent fasting may lower inflammatory markers in your body, such as C-reactive protein (CRP). This can lower your risk for certain diseases and improve your overall health.
Can Intermittent Fasting Slow Down MASLD?
Intermittent fasting may help slow down how fast your MASLD progresses. That’s because fasting may lower the amount of fat in your liver.
People with MASLD who did alternate day fasting for three months along with exercise had:
- About 5.5% lower liver fat
- Lost 5% of their body weight
- Lower waist circumference
- Lower liver enzyme levels
“Whenever someone loses 3%-5% of their body weight, [we’ll generally see lower amounts of] liver fat,” says Varady, who was one of the co-authors of the study. “It’s a downstream effect of overall body fat loss.”
Alternate day fasting may also lower about 20% of your liver fat. But eating fewer calories may only lower liver fat by 15%, according to one study. The fasting group also lost more fat in general and had lower HbA1C levels — a marker for type 2 diabetes.
A few things to keep in mind
“It’s not surprising that the intermittent groups lost more weight and saw more liver fat reduction, because they consumed less calories,” Balakrishnan says. “MASLD patients who try intermittent fasting need to remember that the sources of their calories matter.”
Balakrishnan says to make sure your diet includes healthy foods, such as:
- Fruits
- Fresh vegetables
- Whole grains
- Foods high in lean protein (to preserve muscle mass)
- Foods low in saturated fat
“Otherwise, you may not get the nutrients you need,” Balakrishnan says. “And you may not lose as much weight.”
Who Shouldn’t Do Intermittent Fasting?
Although fasting is safe for most people who live with MASLD, you may need to be more careful if you have certain conditions.
Talk to your doctor or nutritionist if you:
- Have diabetes
- Are under the age of 18
- Are over the age of 65
- Have heart or kidney disease
- Have low blood pressure
- Had an eating disorder in the past
- Are pregnant or breastfeeding
Diabetes
Some people may use intermittent fasting to manage their type 2 diabetes. Before you try any diet changes, always talk to your doctor first.
“There are several diabetes medications, like insulin or sulfonylureas, that will need to be stopped or adjusted before the patient starts any fasting protocol,” says Varady.
Circadian rhythms and fasting
It also may be hard for certain groups of people to do intermittent fasting, says Grace Derocha, RDN, CDCES, a national spokesperson for the Academy of Nutrition and Dietetics in Detroit, Michigan.
“It can be challenging to stick to this approach if you’re a night shift worker, since you’re already struggling with changes in your circadian rhythms,” she says. Circadian rhythm is your body's way of keeping you on a sleep-wake schedule.
A recent study found that intermittent fasting and a regular lower calorie diet both helped evening shift workers lose weight. In other words, there wasn’t a difference between the diets.
How to Safely Start Intermittent Fasting
With MASLD, Varady suggests starting with an alternate day fasting diet. That’s because ADF can help you lose more visceral (fat around your internal organs) compared to time-restricted fasting.
“ADF produces twice as much weight loss as time-restricted eating, when you eat all food within an eight-hour window,” Varady says. “More weight loss produces more liver fat reductions, so alternate day fasting will have faster and more beneficial effects.”
How to try alternate day fasting
On fast days. Only eat about 25% of your usual calories on the days you fast.
For most people with MASLD, that’s about 500-600 calories. Try to eat them all in one meal, such as at lunch.
On non-fast days. Eat your usual amount, generally around 2000-2500 calories.
It’s important to keep it healthy, though. “If you eat huge amounts of processed food, you’ll negate all of the benefits of fasting,” Balakrishnan says.
Try to follow the American Heart Association’s daily guidelines:
- 2 1/2 cups of vegetables
- 2 cups of fruits
- 3-6 servings of whole grains, such as a slice of whole-grain bread, a cup of cereal, or 1/2 cup of cooked brown rice
- 3 servings of low fat or fat-free dairy, such as skim milk or nonfat yogurt
- 5 1/2 ounces of lean protein such as chicken or fish
- At least 5 ounces per week of nuts, seeds, beans, peas, or lentils
- 6-8 ounces of fatty fish such as salmon, mackerel, or sardines
How to try time-restricted eating
If you find ADF too hard, it’s fine to try time-restricted eating, Balakrishnan says.
To start, try to not eat for 12 hours a day. As you get more comfortable, you can slowly lengthen the time during which you don’t eat. Work up until you have fasted for 16 full hours.
With MASLD, time-restricted eating might look like:
Morning. Drink water, tea, or black coffee.
Noon. Eat your first meal.
4 PM. Eat your second meal.
8 PM. Eat your third meal
After 8 PM. Drink water or herbal tea until bedtime.
Other approaches
If you find either approach too hard, don’t worry about it, Balakrishnan reassures. Focus on eating an overall heart-healthy diet.
While ADF appears to help you lose the most weight overall, other weight loss strategies can also help, such as:
- Short-term fasting
- Time-restricted eating
- Simply lowering the amount of calories you eat
“When it comes to MASLD, the best way to lower liver fat is through calorie restriction, which leads to weight loss,” Balakrishnan says. “I tell my patients that if intermittent fasting works for them, that’s great, but if it doesn’t, there are plenty of other ways to reduce calories and lose weight.”
