The conditions that doctors treat as separate problems—obesity, Type 2 diabetes, Alzheimer’s, heart disease, and even polycystic ovary syndrome—may share a single underlying driver: insulin resistance.

Insulin resistance develops quietly, long before symptoms appear, and it is far more responsive to lifestyle than most people realize.

What Insulin Does

After we eat carbohydrates or sugar, glucose enters the bloodstream, triggering the release of insulin—a hormone that helps move sugar out of the blood and into the muscles and liver, where it can be used for energy or stored for later.

When this system is working well, blood sugar rises briefly after a meal and then returns to normal.

“Without insulin working properly, sugar stays in the bloodstream instead of getting into the cells that need it,” Chantelle van der Merwe, a registered dietitian, told The Epoch Times. 

Think of the body as a house made up of many rooms—your cells—and of sugar as the fuel that keeps everything running, she said. Insulin acts like a key that unlocks the doors of those rooms, allowing the fuel to enter and be used.

“If there’s extra sugar, insulin helps store it in the liver and muscles for later—like putting leftovers in the fridge,” van der Merwe said.

However, insulin does far more than manage blood sugar. It plays a central role throughout the body, influencing how cells grow, how they use energy, the production of other hormones, and even whether cells survive or die.

“Insulin is a master metabolic hormone influencing virtually every tissue in the body,” Dr. Sunil Kumar, lifestyle medicine physician, told The Epoch Times.

When insulin signaling breaks down, the consequences ripple across nearly every major organ system, making insulin resistance not just a consequence of disease, but a driver of it.

The Conditions Insulin Drives

When blood sugar rises repeatedly, insulin is released more often. Over time, this constant demand can cause cells to become less responsive, a state known as insulin resistance. The body compensates by producing even more insulin, and a damaging cycle takes hold.

Insulin resistance is the common underlying mechanism behind obesity, Type 2 diabetes, fatty liver disease, cardiovascular disease, and polycystic ovary syndrome, Kumar said.

“Insulin resistance is linked to an estimated 42 percent of heart attacks and contributes to several cancers, including breast and colorectal cancer,” Kumar added.

Because insulin plays such a central role across multiple systems, the brain is especially vulnerable when insulin signaling breaks down, van der Merwe said. Brain insulin resistance refers to the failure of brain cells to respond properly to insulin, which can impair cognition.

The metabolic disturbances seen in Type 2 diabetes closely resemble changes observed in the brains of people with Alzheimer’s disease. This is why Alzheimer’s is sometimes referred to as Type 3 diabetes.

Reproductive health is also closely tied to insulin signaling. Chronically high insulin levels contribute to irregular menstrual cycles and fertility challenges, and are widely considered a major driver of PCOS.

Finally, insulin resistance affects how the body stores fat and responds to diet and exercise. In insulin-resistant states, fat breakdown is impaired, more fat is stored in organs, and weight and fat loss become harder to achieve, regardless of effort, she said.

“Addressing insulin resistance early is a powerful preventive intervention,” Kumar said.

Improve Insulin Sensitivity

The encouraging part is that insulin resistance is not fixed, and daily habits play a much bigger role than many people realize.

Exercise is one of the most powerful tools for improving insulin sensitivity. Both aerobic activity—such as walking, cycling, or swimming—and resistance training help muscles absorb glucose without needing insulin.

Exercise also improves how sensitive muscle cells are to insulin at the receptor level, van der Merwe said. This means that even insulin-resistant muscles can take up glucose from the bloodstream during movement, naturally lowering insulin levels during and shortly after exercise, with the effects lasting up to 72 hours after a workout.

“Doing calisthenics or light weights for 10 to 15 minutes a day is enough to start noticing change,” Sandra Arevalo, a registered dietitian nutritionist, told The Epoch Times. “There’s no need for a gym—you can do it at home with light dumbbells, or even water bottles.”

Sleep and stress also play an important role. Poor sleep and chronic stress raise cortisol levels, which worsens insulin resistance, van der Merwe said. In fact, just one night of partial sleep deprivation—around four hours—can reduce insulin sensitivity by 25 percent.

What we eat matters too. “Fiber, fiber, and more fiber,” is the dietary change van der Merwe sees making the biggest difference. “It’s also one of the biggest things missing in the diets of people struggling with insulin resistance,” she said.

Fiber slows glucose absorption and improves insulin response. Vegetables, legumes, whole grains, nuts, seeds, and fruit are all important sources—but quantity matters.

“People often say they eat these foods,” van der Merwe said. “The issue is they’re not eating enough of them to have a meaningful metabolic effect.” Women under 50 need at least 25 grams of fiber per day, while men need around 38 grams, and it’s only slightly less for those over 50. “One cup of cooked vegetables provides roughly five grams of fiber, meaning a single salad or one serving of vegetables a day is nowhere near enough.”

Van der Merwe recommends pairing your carbs with either protein or healthy fats, as they will slow the absorption of carbs, thereby reducing the need for excessive insulin production. Refined carbohydrates and liquid calories—sugary drinks, fruit juices—should be limited, as they cause rapid insulin spikes without satiety.

If cutting carbohydrates completely or carefully choosing them feels unrealistic, a simple strategy to eat carbs at the end of the meal could be useful. Having starches after vegetables and protein produces a smaller rise in blood glucose and insulin.

Timing Is Also a Factor

One often-overlooked dimension is when we eat. Insulin follows a natural daily rhythm, rising in the morning and falling later in the day. What you eat upon waking has a greater impact on insulin control than the same food eaten in the evening.

In a small study of 24 adults, researchers gave participants a standard glucose drink—similar to a sugary beverage—in the morning, afternoon, and evening on different days. The most insulin was released in the morning, and less later in the day. In fact, the afternoon and evening insulin patterns looked similar to what’s often seen in people with Type 2 diabetes.

“Insulin resistance is not a life sentence,” Kumar said.

Ultimately, the goal is not dietary perfection but physiological alignment, meaning building habits that work with the body’s natural metabolic rhythms rather than against them.