The Role of Insulin in a Ketogenic Diet

The ketogenic diet shifts how your body processes energy, largely through changes in insulin activity. Insulin, a hormone produced by the pancreas, plays a central role in regulating blood glucose and fat storage. When carbohydrate intake drops below 50 grams per day, insulin levels typically fall, allowing the body to switch from burning glucose to fat for fuel.

How Insulin Works in the Body

Insulin acts as a gatekeeper for glucose entering cells. After eating carbohydrates, blood sugar rises, triggering insulin release. This process helps store excess glucose as glycogen in the liver and muscles. When glycogen stores are full, insulin promotes fat storage. On a standard British diet containing 200-300 grams of carbs daily, insulin remains elevated throughout the day.

Insulin Resistance and Metabolic Health

Chronic high insulin levels may contribute to insulin resistance, where cells stop responding efficiently to the hormone. Research indicates that low-carbohydrate diets can improve insulin sensitivity within weeks. A 2018 study in Diabetes Therapy found that people with type 2 diabetes following a ketogenic approach reduced their insulin medication needs by over 50% on average (Hallberg et al., 2018).

What This Means in Practice

Reducing insulin secretion through carbohydrate restriction has practical implications for UK shoppers. At Tesco, a typical keto shopping basket might include:

500g of mature cheddar (£3.20)
400g of smoked salmon (£5.50)
1kg of cauliflower (£1.15)

These foods provide fat and protein while keeping net carbs low. During colder months when root vegetables dominate British cuisine, focusing on above-ground vegetables helps maintain ketosis.

Frequently Asked Questions

Does the ketogenic diet eliminate insulin production?

No. The body still produces insulin on keto, just at lower levels. Even protein intake stimulates some insulin release, though far less than carbohydrates.

How quickly do insulin levels drop on keto?

Most people see significant reductions within 48 hours of restricting carbohydrates to 20-50 grams daily. Full adaptation typically takes 4-6 weeks.

Can keto help if I don’t have diabetes?

Yes. Research shows improved metabolic markers even in healthy individuals, including better blood sugar stability and triglyceride levels (Volek et al., 2008).

The Bottom Line

Insulin modulation forms the foundation of how ketogenic diets work. By keeping carbohydrate intake low, the diet reduces insulin’s role in fat storage while promoting fat burning instead. This metabolic shift may explain why many people find keto effective for weight management and blood sugar control. If you’d rather not do the macro maths yourself, the Keto Dieting app does it for you on Google Play and the App Store.

Educational only — not medical advice. This article is for general information. Speak to your GP before changing your diet, especially if you have type 1 or type 2 diabetes, kidney or liver disease, are pregnant or breastfeeding, or take medication for blood pressure, cholesterol, or blood glucose.

References

Hallberg SJ, McKenzie AL, Williams PT, et al. (2018). Effectiveness and Safety of a Novel Care Model for the Management of Type 2 Diabetes at 1 Year: An Open-Label, Non-Randomized, Controlled Study. Diabetes Therapy. https://doi.org/10.1007/s13300-018-0373-9
Volek JS, Phinney SD, Forsythe CE, et al. (2008). Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids. https://doi.org/10.1007/s11745-008-3274-2