Intermittent fasting: How to lose fat by fasting (Dietitian tips)

Key Points

• Intermittent fasting means eating within a specific time window and fasting for the rest of the day.
• You may lose weight, burn fat, and reap other health benefits through intermittent fasting, but it is not for everyone.
• Various intermittent fasting plans exist, including the 5:2 diet, alternate day fasting (ADF), eat stop eat, and the Warrior diet.
• Before starting intermittent fasting, it’s a good idea to consult a healthcare provider and a Registered Dietitian for personalized advice.

Most weight loss plans focus on what you eat, but intermittent fasting (IF) flips the script. During intermittent fasting, you eat only during specific times of the day and abstain from food the rest of the time.

The length of these time restricted eating plans varies depending on the specific IF schedule you choose. This approach to dieting has many followers—and for good reason.

Let’s explore the benefits of intermittent fasting, the types of fasting plans, and what may work best for you.

Benefits of intermittent fasting

The intermittent fasting benefits include weight loss, improved heart health, and reduced inflammation.

The benefits of an intermittent fasting plan include:

Weight loss

Intermittent fasting can help you lose body weight by creating a calorie deficit. A review of over 40 studies showed that you could lose 7 to 11 pounds in 10 weeks. However, some other research shows no difference between intermittent fasting and regular reduced calorie restriction.

Lower chronic inflammation and improved heart health

It lowers the risk of chronic inflammation and conditions like type 2 diabetes and heart disease, lowers cholesterol, and helps control high blood pressure. It also positively impacts metabolic disease risk markers, such as cholesterol levels and blood pressure.

Simplicity in meal planning

Many people find intermittent fasting plans easy to manage since they only need to plan meals within a specific time window. Plus, because fasting plans don't dictate what foods to eat, you can enjoy your favorite foods without worrying about food group restrictions.

Boosts motivation

The rapid weight loss can motivate some people to become more active, eat healthier, and eventually maintain their weight long term with well-balanced meals.

Types of intermittent fasting plans to lose weight

The most common types of intermittent fasting include:

12:12

12:12 is the simplest form of intermittent fasting. It involves not eating all your meals within a 12-hour window and fasting for the 12-hour period in between. It's a great fasting plan for beginners.

For example, if you complete your dinner by 8 pm, you may eat breakfast at 8 am the next day. This type of eating window is quite doable, particularly since you may be asleep for a large part of the fasting period.

Because your eating period is longer than with other IF plans, your weight loss might not be as significant as it would be with longer fasting windows. However, this may be easier to sustain in the long term.

14:10

The 14:10 plan is a bit tougher than the 12:12 plan since you fast for 14 hours straight.

For example, if you finish dinner by 8 pm, your next meal will be brunch at 10 am the next day. This plan can be more challenging, but it's great if you want to fit in a morning workout before you eat.

16:8

The 16:8 time restricted eating pattern is the most common type of IF plan. It involves no calorie intake within a 16-hour eating window and eating all your meals in 8 hours.

You can choose the eating window that works best for you. A popular choice is to have the first meal at 12 pm, finish dinner by 8 pm, and then fast until noon the next day.

5:2 or the 'Fast diet'

The 5:2 diet is a more aggressive fasting plan. Here, the eating pattern is to fast for 2 days a week and eat regular meals on the other 5 days.

On the 2 fasting days, the goal is to reduce calorie intake to 500 calories for females and 600 calories for males. On the other days, according to the diet, you do not have to worry about calorie counting. You are also free to space the 2 days of fasting out during the week as you wish.

Does the 5:2 diet work for weight loss?

Overall, there isn’t enough science to prove whether this diet works. Some studies suggest that the 5:2 diet is as effective as continuous calorie restriction for weight loss.

According to Registered Dietitian, Rita Faycurry RD, “The 5:2 diet isn’t for everyone. Even though it doesn’t restrict calories to five days a week, you might not lose weight, and you could even gain weight if your eating habits are unhealthy. Eat balanced meals with whole foods, lean meats, and healthy fats, and practice mindful eating with portion control.”

Eat stop eat

The eat stop eat fasting plan includes a 24-hour fast on up to two non-consecutive days a week. So, for example, if you finish your dinner at 8 pm on one day, you do not eat until 8 pm the next day.

The eat stop eat plan is not the same as the 5:2 diet. Here's how it differs:

• The 5:2 diet involves restricted calories on fasting days, while eat stop eat recommends a total 24-hour fast.
• The 5:2 diet does not specify that fasting days must be non-consecutive, but the eat stop eat plan requires you to space your fasting days out (if you choose to have more than 2 fasting days a week).

Alternate day fasting (ADF)

Alternate-day fasting (ADF) is exactly what it sounds like. It's a variant of intermittent fasting in which you fast for one day and eat during the other.

On fasting days, some people may choose not to eat anything, but others may consume as little as 500 calories in the day. On days when you eat, there is no calorie restriction. When you fast, you are allowed water, black, unsweetened coffee, and tea.

Does alternate day fasting help you lose weight?

Some studies found no difference between alternate day fasting (ADF) and regular daily calorie restriction. However, other research paints a different picture. Some studies suggest that ADF is more effective for weight loss in obese adults than the 5:2 diet and time-restricted eating (TRE) plans.

But remember, this level of weight loss can also be achieved without intermittent fasting. It’s all about finding what works best for you.

Faycurry RD explains, "The research on appetite and ADF (Alternate Day Fasting) is mixed—some studies say it reduces hunger, while others find no effect. Ultimately, what really matters is eating well-balanced meals with whole foods and minimizing processed foods in the right proportions."

Warrior diet

The warrior diet is a very extreme form of intermittent fasting, and experts aren't convinced it's necessary or sustainable long-term. It's claimed to be based on the eating patterns of ancient warriors, aiming to promote fitness and enhance brain function.

Following this diet involves a heavily restricted diet for 20 hours, followed by eating as much as you like at night within a 4-hour eating window. While there is no restriction on what you can eat, the diet does recommend leaning towards nutrient-dense and whole foods rather than processed foods. On fasting days, you are encouraged to drink non-caloric beverages like water, black coffee, and tea.

"There aren't any studies specifically proving this diet works, but like other intermittent fasting plans, you can achieve weight loss and fat burning if you maintain a calorie deficit and eat healthy foods along with non-caloric fluids. Keep in mind that this type of diet is very intense, and many people might find it hard to stick to in the long term. Also, there is some concern that this diet may trigger binge eating or other disordered eating habits," Faycurry RD cautions.

Getting started with intermittent fasting? Consider consulting a Registered Dietitian for a personalized nutrition guidance. Use Fay to find a Registered Dietitian near you, covered by your insurance.

Best foods to eat to lose fat by fasting

Faycurry RD says, "Although the guidelines for intermittent fasting mostly revolve around time, your best bet for an effective weight loss eating plan will be through foods full of nutrition, fiber, protein, and healthy fats. I recommend a balanced diet like the Mediterranean Diet for sustained weight loss."

The Mediterranean Diet is more of a lifestyle that focuses on well-proportioned, whole, natural foods and moderate physical activity for healthy living.

Here are foods to eat:

• Whole foods: It prioritizes fresh vegetables, fruit, whole-grain bread, pasta, and rice.
• Healthy fats: Olive oil is a staple, replacing less healthy fats like butter and nuts.
• Fish and lean meats: Seafood and chicken are preferred; red meat and processed meats are enjoyed occasionally.

A Mediterranean diet eating plan is also heart healthy and helps stabilize blood sugar levels.

How does intermittent fasting burn fat?

Intermittent fasting (IF) can help you burn fat by creating a calorie deficit over time, which is essential for weight loss. Basically, you eat fewer calories during your eating windows, and your body starts using stored fat for energy during fasting periods.

If you're aiming to lose weight, remember that intermittent fasting and time restricted eating isn't a free pass to eat anything you want.

Indulging in high-calorie, ultra-processed foods or large portions can still lead to weight gain. Be mindful of what and how much you eat to lose weight by fasting.

Is intermittent fasting right for you?

A study found that intermittent fasting results in similar weight and fat loss compared to traditional dieting methods.

Intermittent fasting, and certainly more extreme forms of fasting, like the Warrior diet, are not for children, people who are pregnant or breastfeeding, those with heart conditions, or those at risk of eating disorders or disordered eating patterns.

While time restricted feeding programs like fasting can be effective for weight loss, it’s important to remember that it's not the only option out there. 

Faycurry RD notes, “If fasting doesn’t suit you, don’t worry—there are plenty of other diet plans that might work better for you. It’s always a good idea to consult with a Registered Dietitian to find a personalized nutrition plan that fits your needs and lifestyle."

Find out if fasting is right for you. Fay connects you to a Registered Dietitian near you, covered by your insurance.

The views expressed by authors and contributors of such content are not endorsed or approved by Fay and are intended for informational purposes only. The content is reviewed by Fay only to confirm educational value and audience interest. You are encouraged to discuss any questions that you may have about your health with a healthcare provider.