SIMPLE’s intermittent fasting picks according to belly type

Written by Krista Scott-Dixon

Medically reviewed by Louise Bula, RD

Published on December 12, 2023 | Updated on March 28, 2024

We’ve all been there: that day when you put on your pants and … ouch. 

The waistband is scrunching your stomach. The elastic isn’t elastic-ing quite enough. Or the belt holes seem to have suddenly shifted in the wrong direction. 

Whatever the reason, you might have had at least one encounter with clothing waistbands that made you think: could I change my belly shape and size? 

And, if you’ve been practicing (or interested in) intermittent fasting — alternating periods of eating with periods of abstaining from food — you might also have wondered: is there some kind of intermittent fasting that might be right for my belly type? 

In this article, we’ll explore the question of whether intermittent fasting can help you to lose belly fat, particularly whether intermittent fasting according to belly type is even a thing. 

Fancy trying intermittent fasting out? Take our SIMPLE quiz, and we’ll give you a hand!

Best intermittent fasting schedules according to belly type

When it comes to intermittent fasting based on belly type, it can help to understand what affects your belly size and shape.

Each of us stores body fat, aka adipose tissue, in different places. Where exactly our body stores its fat depends on many factors,[4] including our:

• genetics [5,6]
• hormones
• age
• metabolism
• amount of body fat 

So, although belly size and waist circumference can be influenced  by intermittent fasting (because intermittent fasting can help folks lose body fat) [7], belly type is not as affected by intermittent fasting per se.

Fat isn’t just an inert pile of “stuff.” Rather, it’s a metabolically and hormonally active tissue that secretes all kinds of hormones and cell signaling molecules and helps our brain know how much stored energy we have available. 

For good health, we want some body fat, but not too much — especially not too much in certain places.

Subcutaneous fat

Subcutaneous fat is the fat you can pinch. 

It’s the stuff just under your skin that you can grab, that gives some folks those adorable cheek dimples or plush booties, and that pads the soles of our feet so we aren’t crunching our foot bones with every step.

We have subcutaneous fat all over our bodies. But where exactly it goes, again, depends on many factors. For instance, thanks to the effects of genetics, you probably put on subcutaneous fat like at least one of your close relatives does.

Women generally have more subcutaneous fat than men, particularly around the hips and thighs.[8] Age-related changes, hormonal fluctuations, and lifestyle factors such as diet and physical activity also impact its levels. 

Folks who have more subcutaneous fat around their middle are more likely to be:[4]

• men and/or supplementing testosterone; or
• women who also have larger breasts and put on more fat in the upper body and face (and who might have a sister, mother, and/or aunt who’s shaped the same);
• women who have had at least one pregnancy; and/or
• women who have gone through menopause (so the hormonal environment has shifted).[9]

Thanks to the effects of estrogen, many women also put on more subcutaneous fat in their lower belly, rather than higher up, closer to their ribs.

In general, subcutaneous fat seems to be healthier than its cousin, visceral fat.[2,10]

Visceral fat

Visceral fat is fat around and within our viscera, or internal organs in our abdominal cavity.

While we need some visceral fat to cushion our organs (we don’t want them smashing around in there while we’re running and jumping, for instance), too much can be a problem.[2] 

Visceral fat can infiltrate (or deposit itself) into internal organs like our heart, kidneys, and liver and affect their function. 

Unfortunately, this type of fat can significantly disrupt the health of those organs as well as our general metabolic health and increase our risk of diseases like type 2 diabetes, cardiovascular disease, and/or chronic kidney disease.[11–13] 

Folks who have more visceral fat are more likely to:

• be older;
• be highly stressed (because chronic stress releases cortisol, which can contribute to fat deposits around the midsection);
• be less physically active;
• have more body fat in general; and/or
• be of South or East Asian descent.[6,14]

Belly bloating

This isn’t belly fat — it’s belly distention. You might feel “stuffed,” or feel pressure in your abdomen. Maybe your belly even feels hard to the touch. You might notice you start the day feeling normal and end the day feeling like an over-inflated balloon.

This can occur for many reasons, such as:[15]

• a food intolerance that causes intestinal gas (so your “belly type” might actually be, for instance, “lactose belly” or “can’t digest broccoli belly”)
• slow digestion that means food stays in your gastrointestinal tract longer
• constipation
• fluid retention during your menstrual cycle or with perimenopause

If this is a persistent problem beyond a day or two of “Oof, I shouldn’t have eaten that high-fiber double-sauerkraut triple-cheese bean casserole and washed it down with extra-fizzy soda,” consult your doctor for guidance.

OK, so what’s the best method of intermittent fasting based on belly type?

Just like there are different belly types, there are many different types of intermittent fasting, each with its own pros and cons. 

At SIMPLE, the approach we recommend most is time-restricted eating, or TRE. With this method, you fast for several hours, most likely overnight, then enjoy an “eating window” of normal eating. 

There are many types of TRE schedules, such as:

• 12:12 (12 hours fasting + 12 hours eating)
• 14:10 (14 hours fasting + 10 hours eating)
• 16:8 (16 hours fasting + 8 hours eating)

The flexibility of TRE makes it an ideal approach for all body types. So, should you be “fasting according to belly type”? Not really, since all types of belly fat will change with intermittent fasting. 

While research definitely suggests that time-restricted eating can help people lose visceral fat, it can also help us lose other fat too.[16]

Let’s explore further.

How does intermittent fasting affect belly fat?

Fasting involves a period of several hours without food. Somewhere around 8–12 hours after our last meal, our body runs out of fuel from that meal and needs to use fuel that we’ve stored, i.e., our body fat. This is the fasted state.

Luckily, most of us have some fat to burn, including belly fat. (Check your SIMPLE app during your fasting periods to see your fat-burning status change in real time!)

Is intermittent fasting a good method for burning belly fat?

Research suggests that visceral fat may be more sensitive to fasting — in other words, our body might burn deep abdominal belly fat first during fasting periods when our last meal runs out.[17]

However, other evidence suggests that all belly fat types can be reduced with intermittent fasting. For instance, one study found that after 12 weeks of intermittent fasting, people with prediabetes had lost:[18]

• subcutaneous fat;
• visceral fat;
• liver fat; and
• fat in the pancreas (where insulin is produced).

All of these changes are linked to health benefits, so it’s a win all around.

What factors impact your ability to lose belly fat?

There are some other key factors that can affect your ability to lose belly fat.

Nutrition

In general, if we eat too much energy (aka too many calories), we’ll gain weight. Conversely, if we eat fewer calories than we burn, we’ll lose weight. 

So, while intermittent fasting allows you to eat a flexible diet, if your goal is weight loss, then double-check how many calories you’re consuming. (Try logging your food in your SIMPLE app for personalized nutrition insights and recommendations. Start by taking our SIMPLE quiz, and you’ll master your nutrition game in no time!)

While one common intermittent fasting side effect is being hungry, you’ll find yourself less hungry if you include more protein, fruits, vegetables, and fiber in your diet — which means you’ll eat less but feel more satisfied. 

For instance, one study found that intermittent fasting combined with a higher-protein diet (with protein at most meals) led to more fat loss than calorie restriction (aka a standard “diet”).[19]

On the flip side, look for ways to eat fewer highly processed foods (think: pastries, candy, packaged snack foods, sugar-sweetened drinks, and so on). Some evidence suggests that consuming a lot of fructose — a type of sweetener used in many processed foods and drinks like soda — can contribute to belly fat.[20]

Sleep

Sleep and visceral fat have a bidirectional relationship. In other words, having more visceral fat can make your sleep worse, and sleeping worse can increase your chances of having more visceral fat.[21–23]

However, this can also work in a positive direction: improving your sleep will often help you lose belly fat more easily … and losing belly fat can also improve your sleep. 

For many people, this may mean a trip to your doctor to be evaluated for sleep issues, such as sleep apnea.

Stress

Chronic stress may add to our belly fat woes. Cortisol, one of our key stress hormones, can increase fat deposits around our middle.[24] (Not to mention the fact that many of us eat when we’re stressed!)

It may seem counterintuitive, but tackling your stress with activities like meditation or time in nature may actually help you lose belly fat as well.

Exercise and physical activity

It shouldn’t be a shock that being physically active helps manage belly fat, so let’s look more closely at that.

Is exercise necessary when intermittent fasting to lose belly fat?

Strictly speaking, you don’t need to exercise to lose belly fat. However, it works much better when you do.

For instance, one study compared groups who were restricting calories and either doing aerobic exercise, resistance training (e.g., lifting weights), or a combination of everything.[25]

Researchers found that the combination of both eating less and exercising in different ways was the most effective. People doing the combination lost more visceral fat (aka belly fat) compared to those in the aerobic- or resistance-only groups. 

Bonus: The combination group also enjoyed the most improvements in insulin sensitivity, physical function, aerobic capacity, gait speed, and knee strength. In other words, wins all around.

Benefits of exercising while intermittent fasting

Combining exercise with intermittent fasting (and good nutrition, of course) is one of the best ways to lose belly fat.

You can exercise while you’re actually fasting — i.e., during your fasting window — as well as during your eating window. 

• During the fasting window, it’s generally better to do “low and slow,” such as walking, easy hiking, or leisurely bike riding or swimming. Here, you’re almost exclusively using body fat for fuel, so this will chip away at that belly fat nice and easy.
• Save the more intense exercise, such as hardcore hikes, CrossFit, or fast-paced runs, for your eating window after you’ve had at least one meal. While you’re not using primarily fat during intense exercise, you are able to work harder — which means more calories burned and more belly fat lost in the long run.

Exercise helps us regulate insulin and blood sugar better, clears the fatty acids out of our liver, and helps our body more effectively use stored body fat for fuel from other places like our muscles (aka intramuscular triglyceride).[26]

Building muscle mass — a key benefit of exercise, especially resistance training — helps improve our metabolic health as well as our everyday function (think: going up and down stairs, carrying groceries, etc.).[27]

Some evidence suggests that TRE combined with exercise may even improve VO₂  max (aka our body’s ability to take in and use oxygen).[28] In turn, this might make workouts a little easier — which often helps us feel more motivated to do more.

Drawbacks of exercising while intermittent fasting

Some people might find they have less energy in their fasting window. No problem — take a look at your schedule and figure out when it might be best for you to exercise during your eating window.

If you’re doing intense athletic training, make sure to eat before and after a hard workout to provide enough fuel in the tank, as well as nutrients for recovery afterward.

Check out this article for more on intermittent fasting and working out.

4 tips on choosing the best intermittent fasting schedule for your belly type 

1. Check with your doctor about your overall health and risk.

Your belly size and type — along with your genetics / ethnicity, age, body composition (ratio of lean mass to body fat), and other medical conditions will shape your overall health situation. 

So, consult with your healthcare provider to find out what the best path might be for you — as well as what type of intermittent fasting might be a fit for your unique situation.

2. Look for the schedule that keeps your stress low.

Since stress is a factor in belly fat, find an intermittent fasting approach that’s as easy as possible for you to follow — especially if you’re an intermittent fasting beginner.

Two of the most common intermittent fasting mistakes are either going too hard, too fast, too soon, or being too strict with oneself about sticking to an intermittent fasting schedule. 

Transition to your intermittent fasting lifestyle gradually, looking for a schedule that aligns with your needs and preferences.

3. Go for the combo.

Good health behaviors work together. You’re more likely to lose body fat by combining fasting with nutrition, exercise, sleep, and stress management. 

So, along with whatever intermittent fasting schedule you choose, also look for ways you can improve your other health and lifestyle choices.

4. Try a slightly longer fast.

Start with something easy-ish, like a 12-hour fast (and make sure to put your sleep time in the middle of that … that’s 8 hours out of the way right there!). As you get more comfortable, try fasting a little longer, like 14 or 16 hours. Research suggests that the longer the fast, the more weight you’re likely to lose.[29] 

We don’t, however, recommend fasting beyond 18 hours as there is no evidence to show any additional benefits. So remember to keep it below 18 hours; that’s the sweet spot!

Written by Krista Scott-Dixon

Medically reviewed by Louise Bula, RD

Published on | Updated on March 28, 2024