Resistant starch improves visceral fat

Introduction

Why should you be aware of visceral fat?

What is visceral fat? Isn’t fat just fat?

Visceral fat is packed deep in the abdomen around organs like your liver, pancreas, or intestines. It forms around organs and vessels. It’s not the fat you see in a mirror. It isn’t the pinchable fat under the skin.

How Does Visceral Fat Develop?

You always have some visceral fat; too much builds up when energy intake and hormonal signals steer extra calories into deep abdominal depots rather than muscle or subcutaneous fat.

Key Contributors

It’s eating more calories than you burn. Surplus calories get stored as fat, including visceral deposits.

Sedentary behavior and low muscle mass reduce energy expenditure and promote abdominal fat storage.

Diets high in refined carbs/sugars, saturated and trans fats, ultra-processed foods, and sugary beverages are strongly associated with central/visceral obesity.

Excess alcohol particularly promotes abdominal and liver fat.

Hormones, stress, and sleep are key factors.

Chronic stress leads to elevated cortisol and preferential fat deposition in the abdominal/visceral area.

Short or poor-quality sleep drives weight gain and visceral fat, partly via appetite and insulin changes.

Endocrine disorders (Cushing’s disease, hypothyroidism, lipodystrophies) can markedly increase visceral fat.

Genetics determine fat distribution (apple vs pear shape) and predisposition to visceral accumulation.

With age, especially in men and post-menopausal women, fat tends to shift toward visceral depots even if weight is stable.

Mechanistically, visceral adipocytes become enlarged and inflamed, secreting more cytokines and adipokines (e.g., IL-6, TNF-α, RBP4) that drive insulin resistance and vascular dysfunction.

Visceral fat is metabolically active and drains into the portal vein, exposing the liver to high free fatty acid flux and inflammatory mediators. This underlies many of its risks.

Atherogenic dyslipidemia (elevated triglycerides, increased small dense LDL, low HDL) is a hallmark associated with excess visceral fat.

Hypertension via vascular inflammation, arterial stiffness, and hormonal effects show up with visceral fat.

Metabolic syndrome becomes a part of the picture. There is a strong increased risk of coronary heart disease, heart attack, and stroke.

Cancer and dementia increase frequently.

You’re likely beginning to get the picture and it isn’t pretty. Colorectal adenomas and cancer are more prevalent with about 3 times the risk of precancerous polyps in those with the most visceral fat.

There is an increased risk of breast cancer and several other malignancies.

There is about 3 times the risk of dementia.

Alzheimer’s disease is likely to show up decades later in those with high mid-life abdominal fat.

Sleep apnea, reduced lung function, heartburn, and sleep difficulties follow.

Hormone function is altered. Sex hormones are imbalanced. Menstrual disturbances, and even reduced fertility can result.

There is a greater surgical risk and complications due to the more difficult access. Not surprisingly, there is a higher cardiometabolic risk.

Overall, visceral fat is a strong predictor of all-cause mortality, independent of BMI (body mass index).

What Actually Reduces and Eliminates Visceral Fat?

You can’t “spot-reduce” visceral fat by doing sit-ups, for example. It responds better to lifestyle changes than subcutaneous fat. It often comes off first with a proper lifestyle modification program.

Here’s the basics of the targets in lifestyle modification. Achieve a modest calorie deficit. This is a slow and steady process. Make changes you can maintain for the long haul.

Achieve a sustained loss of 5–10% of body weight and you will significantly reduce visceral fat and cardiometabolic risk.

This can be diet alone, but it’s much better to combine diet with exercise and preserve muscle mass and function. It also improves insulin sensitivity. That is a major critique of the GLP-1 peptides. Not only fat loss but muscle loss. It can be prevented with adequate protein intake and exercise. More muscle burns more calories. It all fits together.

Your diet should emphasize whole-food and anti-inflammatory foods.

Mediterranean or DASH-style diets with vegetables, fruits, legumes, whole grains, nuts, olive oil, and fish. Definitely try to minimize refined carbs and ultra-processed foods.

Higher protein intake improves satiety and helps preserve or build lean mass, indirectly reducing visceral fat.

Reduce “visceral-promoting” factors like added sugars, refined starches, sugary drinks (including fruit juice), and trans fats. AVOID high fructose corn syrup sweeteners which are the prevalent means for sweetening drinks. High fructose corn syrups (HFCS) was a horrible result of “food science” with so many negative effects. I think most have heard that story but if you haven’t read about it, read about it and abandon it for your own health. Don’t get your children started on that addiction. You wouldn’t teach them how to smoke at an early age, would you?

Avoid heavy alcohol intake.

Avoid ultra-processed snack foods high in refined carbs and industrial fats.

A diet with increased soluble fiber (oats, beans, chia, flax, and many vegetables) is associated with less visceral fat. See the end of this article for a new diet target and a specific new starch recommendation.

Adequate calcium and vitamin D may correlate with lower visceral fat, though causality is less clear.

Intermittent fasting. Especially the timed eating approaches like eating your last meal earlier in the day and not eating again until morning. Some have catchy names like the 16-8 approach meaning 16 hours of fasting and getting your calories confined to an 8 hour window. That improves insulin dynamics.

Visceral fat responds strongly to regular movement; both cardio and resistance matter.

Brisk walking, cycling, jogging, swimming 30 plus minutes/day on 5 days/week will significantly reduce visceral fat.

HIIT (high intensity interval training) can be especially efficient for reducing abdominal and visceral fat.

Resistance / strength training are very valuable (2–3 sessions/week). That improves insulin sensitivity and increases/maintains muscle mass, raising basal energy expenditure and aiding visceral fat loss.

Spot exercises, like sit-ups, harden muscles but do not directly target visceral fat; it’s the systemic energy deficit that matters.

A mix of cardio plus resistance is more effective than either alone for visceral fat reduction.

Aim for 7–9 hours of quality sleep. Chronic sleep restriction promotes weight gain and the deposition of visceral fat.

Manage stress with methods like meditation, breathing exercises, “walks in the woods”, and even deep conversations in relationship will help lower cortisol and break stress-eating cycles.

Avoid smoking, which is associated with more central/visceral fat despite sometimes lower body weight. It is a part of that “skinny fat” syndrome. The visceral fat may not fit the picture of what the overall body looks like.

Keep up daily low-level activity. Walking after meals, taking stairs, standing more all improve glucose handling and reduce fat storage.

For people with significant visceral obesity plus metabolic disease, medical interventions can help, under professional supervision. Weight-loss medications like the GLP-1 agonists and others reduce body weight, visceral fat and improve cardiometabolic markers.

Bariatric surgery produces large, sustained losses of visceral and hepatic fat and achieves major reductions in diabetes and cardiovascular risk in appropriate candidates.

Treating underlying endocrine disorders like Cushing’s syndrome or hypothyroidism is essential if present.

Where Do You Start?

OK. You got the message. Where do you start?

Get some baseline parameters. Measure your waist circumference. Calculate your waist-to-height ratio. Better yet get a body composition scan (DEXA with visceral fat estimate). There are newer electronic scales that pass a micro current through your body while you stand on the scales and give water percentage fat percentage, muscle percentage and even calculate a visceral fat percentage scale weight.

Set a 3–6 month goal of losing 7–10% of your body weight if you are overweight. Do it by adopting diet changes, exercise and the other measures we discussed.

Re-measure every 8–12 weeks. Don’t say it isn’t working if you aren’t seeing results. Go up in your intensity.

Resistant Starch

If you’re a biohacker here’s one you should consider.

There is a food that has been shown in multiple human randomized controlled trials to improve metabolic health, reduce liver fat, and even drive weight loss independent of calorie intake.

Resistant starch is a type of starch that resists digestion in the small intestine and reaches the large intestine intact. There it alters the gut microbiome in clinically meaningful ways.

Biochemically, starch is just a chain of glucose molecules bound together.

Under normal circumstances, enzymes made by your body (like salivary and pancreatic amylase) break starch down efficiently into glucose quickly as it transits your GI system. Glucose gets absorbed in the small intestine and becomes readily available energy.

Resistant starch. There are different types of resistant starch, but we’re focusing on “type 2” resistant starch. It can be found in raw potato, green banana, and high-amylose maize (think corn). Type 2 resistant starch is chemically identical to regular starch. It’s made of the same glucose and the same glucose bonds. The difference is structural, not chemical.

Resistant starch is tightly packed. It’s highly crystalline. It isn’t well hydrated. The glucose chains are arranged in a way that digestive enzymes can’t easily access and break it down for absorption.

Think of it like a bundle of straws taped together.

It’s still a collection of straws. Same straws. Because they’re tightly packed and rigid, it’s much harder to break apart, bend, or manipulate. That’s resistant starch. A different architecture, but still the same chemistry.

So instead of being digested quickly in the small intestine, it resists digestion. It slips past our salivary and pancreatic amylase largely intact and travels through our stomach and the long small intestine relatively intact on its way to the colon.

The large intestine would normally have gut bacteria that harbor dozens of carbohydrate-active enzymes. They have a greater diversity of tools that are able to separate the tightly bound strands of starch and process them. Without those bacteria in our large intestines we can’t break those resistant starches down. There are some gut bacteria that thrive on those resistant starches. They send good signals to the body to promote health. All of this is true unless we’ve murdered them. Many things can harm them including antibiotics, toxins, etc. We want them around as they’re beneficial.

So once resistant starch reaches the colon, bacteria can slowly erode that tightly packed crystalline structure and ferment it.

But instead of turning into glucose absorbed in the small intestine, it reaches the large intestine (colon) and becomes fuel for gut microbes, modifying the microbiome and the hormones microbes produce that communicate to our bodies. This is how resistant starch works.

There was a study published in Nature Metabolism.

A randomized controlled crossover trial that involved overweight people.

A crossover design means that each participant served as their own control. Everyone completed two phases. One phase used a ‘resistant starch’, including 40 grams/day of type 2 resistant starch, and a second phase which was a calorie-controlled starch phase.

This was also an especially rigorous study because the participants’ background diets were controlled. The study was double-blinded. They packaged the food identically and even the investigators didn’t know which diet the participants received.

During the resistant starch phase, the body weight decreased significantly.

The fat mass declined with a specific and meaningful reduction in visceral fat.

They measured and demonstrated improved insulin sensitivity, reduced inflammatory markers, including TNF-α. There was improved levels of proteins involved in lipid metabolism, including ANGPTL4. They noted participants literally excreted more fat, including fatty acids, triglycerides, and cholesterol.

Their data showed that the gut microbiome causally mediates the benefits of resistant starch. The intestines themselves demonstrated improvements in gut barrier integrity and had evidence of reduced “leaky gut.”

Everyone benefited but some benefited much more than others. They kept digging to explain the difference.

The researchers performed fecal microbiota transplants (FMTs) using stool from the human participants after either the resistant starch or control starch intervention. And they transplanted this stool into mice whose native microbiomes had been wiped out by antibiotics.

When they transferred the microbiome from humans who consumed resistant starch into mice who maintained on a uniform diet, what would happen?

The mice with the transplanted bacteria, the gut microbiome, of the people that ate the resistant starch lost weight compared to other mice that were on the same diet. They then “sacrificed” (a medical term for an autopsy) the mice and demonstrated less visceral fat. Note — you can go look at the images of these mice if you go look at the study. Links should be in the bibliography of the website. Very interesting.

Resistant starch supplementation can drive meaningful fat loss, including visceral fat, as demonstrated by MRI in humans in a double-blind, placebo-controlled trial, and that these effects are mediated by changes in the gut microbiome.

Another improvement was a reduction in what’s commonly referred to as “leaky gut.”

Intestinal permeability was assessed. That improved also.

The same issue was noted. Everyone benefited but some benefited much more. Another paper released in Cell Metabolism in 2025 gives some answers.

Again it came down to the specific bacteria living and thriving in the gut.

The investigators went on to discover that baseline microbiome composition strongly predicted who would respond to resistant starch. One particular bacteria, Prevotella, was more prevalent in low responders. When it was present in higher than normal quantities, the resistant starch didn’t perform.

Prevotella competes with other gut bacteria that are more efficient at fermenting resistant starch into beneficial metabolites.

There was another bacterium, Bifidobacterium pseudocatenulatum. That bacteria showed the opposite to Prevotella. It is capable of metabolizing resistant starch, and its presence predicted a stronger metabolic response.

So the balance matters. We want more Bifidobacterium pseudocatenulatum and less Prevotella.

The poor mice had to undergo even more fecal transplants to prove that different ratios had different effects.

If you’re looking to buy the same resistant starch these researchers used, it was high-amylose maize starch (Hi-Maize 260), at a dose of 40 grams per day.

You can also obtain type 2 resistant starch in your diet from unripe green bananas or raw potatoes.