What Is Insulin Resistance?

Insulin resistance occurs when cells become less responsive to insulin's signal to absorb glucose from the bloodstream. The pancreas compensates by producing more insulin, keeping blood sugar normal — for a while. This is why fasting glucose and HbA1c can appear normal for years while insulin resistance is already well established.

Fasting insulin is the earliest detectable marker of this process. A fasting insulin above 10 µIU/mL — even with normal glucose — is a meaningful signal that metabolic dysfunction is developing.

Why It Matters Beyond Diabetes

Insulin resistance is not just a precursor to type 2 diabetes. It is implicated in cardiovascular disease, non-alcoholic fatty liver disease, polycystic ovarian syndrome, certain cancers, cognitive decline, and accelerated aging.

Addressing insulin resistance is arguably the single highest-leverage intervention in preventive health — because it sits upstream of so many downstream conditions.

Metabolic Flexibility

A metabolically healthy person can efficiently switch between burning carbohydrates and fat depending on availability and demand. This is called metabolic flexibility. People with insulin resistance often lose this ability and become overly dependent on glucose — contributing to energy instability, fat storage, and difficulty fasting.

Restoring metabolic flexibility is a key goal of dietary and lifestyle interventions targeting insulin resistance.

• Ability to fast without significant energy crashes
• Stable energy between meals
• Efficient fat oxidation during low-intensity activity
• Reduced post-meal glucose spikes

Nutrition Frameworks

There is no single universally optimal diet for metabolic health. However, several patterns consistently improve insulin sensitivity: reducing ultra-processed foods and refined carbohydrates, increasing dietary protein, prioritizing whole foods, and reducing seed oil consumption.

Low-carbohydrate and ketogenic approaches have strong evidence for improving fasting insulin, triglycerides, and HbA1c — particularly in people with existing metabolic dysfunction. Time-restricted eating and intermittent fasting also show benefit for insulin sensitivity independent of caloric restriction.

The Role of Movement

Skeletal muscle is the primary site of glucose disposal. Resistance training and aerobic exercise both improve insulin sensitivity — through different mechanisms. Resistance training increases muscle mass and glucose transporter expression. Aerobic exercise improves mitochondrial function and fat oxidation.

Even a 10–15 minute walk after meals has been shown to meaningfully blunt post-meal glucose spikes.