Does Fat-Based Food Have a Low Insulin Index?

Short Answer: In most controlled studies, foods that contain more fat and very little carbohydrate tend to produce a lower insulin response than carbohydrate-rich foods. However, fat alone does not automatically mean “low insulin.” The insulin response depends on the total macronutrient composition, portion size, and the testing method used.

There is a general trend — but not a universal rule.

The insulin index measures how much insulin the body releases after eating a specific food, compared to a reference food (usually white bread or glucose).

The concept of the food insulin index was formally introduced by:

• Susanne Holt
• Jennie Brand-Miller

in their landmark 1997 study published in the American Journal of Clinical Nutrition.

They measured insulin responses to 1000 kJ portions of various foods and compared them to white bread (reference = 100).

The key finding: Insulin response does not depend only on carbohydrates. Protein can also stimulate insulin. Fat tends to have a smaller effect.

Pure or mostly fat-based foods include:

• Olive oil
• Butter
• Avocado
• Macadamia nuts

These foods contain minimal carbohydrate and moderate or low protein.

Observed Pattern in StudiesIn the 1997 Holt et al. study:

• Butter produced a very low insulin response.
• Oils produced minimal insulin elevation.
• High-fat foods with negligible carbs had low insulin scores.

Conclusion from Research

There is no strict linear correlation between fat content and insulin index.

However:

• Foods that are high in fat and low in both carbohydrate and protein generally produce the lowest insulin response.
• Foods high in protein may produce more insulin than high-fat foods.
• Carbohydrate-rich foods consistently produce the highest insulin responses.

So the pattern is:

Low carb + low protein + high fat → lowest insulin

High protein → moderate insulin

High carbohydrate → highest insulin

This is consistent with findings from:

• Holt et al., 1997 (AJCN)
• The American Journal of Clinical Nutrition - Effect of a low-fat diet on fatty acid composition in red cells, plasma phospholipids, and cholesterol esters: investigation of a biomarker of total fat intake

Now it becomes more interesting.

Foods like:

• Cheese
• Salmon
• Steak
• Eggs

contain both fat and significant protein.

Protein stimulates insulin secretion via amino acid signaling (especially leucine and arginine). Therefore:

• These foods may produce moderate insulin responses
• Sometimes higher than expected despite low carbohydrates

David Ludwig and colleagues have also discussed how insulin secretion is influenced by protein intake in metabolic studies.

Below is a structured comparison based primarily on the original food insulin index dataset by Susanne Holt and Jennie Brand-Miller published in the American Journal of Clinical Nutrition (1997).

Reference scale:

White bread = 100 (1000 kJ portions)

Important: Values are approximate from published datasets. Insulin index depends on portion standardization (isoenergetic 1000 kJ serving).

1️⃣ Protein Foods

Protein stimulates insulin more than fat, but generally less than carbohydrate.

Exception: Dairy products (like yogurt) can produce disproportionately high insulin responses relative to their carbohydrate content.

2️⃣ Carbohydrate Foods

These consistently produce the highest insulin responses, especially refined starches and glucose.

3️⃣ Fat-Dominant FoodsPure or near-pure fat foods produce minimal insulin response.

This is the most consistent pattern across insulin index literature.

The data supports the conclusion:

Foods that are primarily fat (with minimal carbohydrate and moderate/low protein) generally have the lowest insulin index.

However:

• High-fat + high-carb foods (e.g., croissants) produce high insulin.
• High-protein foods produce moderate insulin.
• Fat alone has little insulinogenic effect.

If fat-based foods produce lower insulin spikes, what are the implications?

Insulin is a hormone that:

• Promotes fat storage
• Inhibits lipolysis (fat burning)

Lower insulin levels may:

• Allow greater fat oxidation
• Reduce hunger in some individuals
• Stabilize blood sugar

However:

⚠️ Fat is calorie-dense (9 kcal per gram).

Therefore:

• High-fat diets may support weight loss if they reduce overall calorie intake and improve satiety
• But excessive fat intake can still lead to weight gain

Weight loss depends on total energy balance + hormonal response, not insulin alone.

Direct answer: Pure dietary fat triggers very little insulin secretion.

Insulin is primarily stimulated by glucose (carbohydrates) and certain amino acids from protein. Fat alone has minimal impact on postprandial insulin levels, especially when carbohydrate intake is low.

The insulin index reflects insulin response per standardized portion. Since fat does not significantly raise blood glucose, the body requires only a small insulin response compared to carbohydrate-rich foods.

Yes. If a meal combines fat with carbohydrates or significant protein, insulin may rise.

For example, pastries (high fat + high carbohydrate) produce a high insulin response. The insulin effect depends on total macronutrient composition, not fat alone.

Yes. Protein stimulates insulin more than pure fat.

Amino acids such as leucine and arginine activate pancreatic insulin secretion. This is why foods like beef, fish, and dairy produce moderate insulin responses even when low in carbohydrates.

Yes, generally. Foods that are predominantly fat tend to have a lower insulin index because fat has minimal effect on blood glucose and triggers very little insulin release. However, if a food also contains significant carbohydrates or protein, the insulin response may be higher.

Generally, yes.

Ketogenic diets restrict carbohydrates, which lowers glucose-driven insulin secretion. Clinical trials show reductions in fasting insulin and post-meal insulin exposure in individuals following carbohydrate-restricted diets.

Yes. Lower insulin levels help the body access stored fat for energy because insulin inhibits fat breakdown. When insulin levels are lower, fat oxidation increases and the body can burn stored fat more easily. However, long-term weight loss still depends on overall energy balance, appetite regulation, and dietary patterns.

Because dairy proteins are insulinogenic. Whey protein strongly stimulates insulin secretion. As a result, yogurt and milk may produce higher insulin responses than expected based on carbohydrate content alone.

No significant increase. Olive oil is almost entirely fat and produces minimal insulin response when consumed alone. However, insulin response may rise if consumed with carbohydrate-rich foods.

Most nuts have low insulin responses. Nuts are high in fat and moderate in protein, with low available carbohydrate. Their insulin index values are typically low compared to grains or refined carbohydrates.

Pure fats rank lowest.

Examples include:

• Butter
• Olive oil
• Heavy cream

These foods contain minimal carbohydrate and therefore produce minimal insulin response.

Refined carbohydrates and glucose-rich foods rank highest.

Examples include:

• White bread
• Boiled potatoes
• Glucose solutions
• Breakfast cereals

These foods rapidly increase blood glucose and trigger strong insulin release.

They measure different things. The glycemic index measures blood glucose response. The insulin index measures insulin response. Some foods (like dairy) have a low glycemic index but a relatively higher insulin index.

Sometimes. Adding fat to carbohydrate-rich meals may slow gastric emptying and reduce glucose spikes. However, total insulin exposure may still be significant depending on carbohydrate amount.

Almost, but not completely. Fat itself has minimal direct insulin effect. However, digestion, incretin hormones, and mixed-meal dynamics can still produce small insulin responses.

Scientific data consistently show that foods composed mostly of fat produce the lowest insulin responses. However, insulin response depends on the full macronutrient composition of a food.

Foods containing both fat and carbohydrates can still produce high insulin responses.

Understanding how different foods affect insulin levels can help you make smarter choices for metabolic health. The insulin index shows how strongly foods stimulate insulin production, even if they don’t contain a lot of carbohydrates.

To explore the full database, visit our Insulin Index of Foods – Search Any Food | Complete Database.

Search any food in our Insulin Index Chart (Updated 2026) and see how different foods affect insulin response based on scientific data.

To make it easier to navigate, we’ve organized foods into clear categories. You can explore the insulin response of common foods in these guides:

• Discover the insulin index of fruits and learn which fruits cause a lower insulin response:
• See the insulin index of vegetables and find out which vegetables are best for stable insulin levels
• Check the insulin index of fish and seafood to understand how protein-rich foods affect insulin:

If you’re concerned about metabolic health, you may also want to take our quick assessment to see whether your symptoms may be related to insulin resistance.

• Take the insulin resistance test
• Learn whether fat-based foods tend to have a low insulin index and why foods rich in fats usually cause a much smaller insulin response compared with carbohydrate-rich foods.

These resources can help you better understand insulin responses and choose foods that support stable energy, balanced blood sugar, and long-term health.

Author: InsulinGuru Research Team

Focus: Nutritional research and insulin response analysis

This article was prepared using peer-reviewed metabolic research and insulin index datasets.

Insulin index values on this page are based on peer-reviewed research, primarily the foundational study by Holt et al. (American Journal of Clinical Nutrition, 1997), which measured postprandial insulin response over two hours after standardized 1000 kJ portions. Where vegetables were not directly tested in clinical trials, values are clearly identified as estimates derived from carbohydrate composition, fiber content, and established metabolic research. This approach ensures transparency while reflecting current scientific evidence.

• Holt SH, Brand-Miller JC, Petocz P. An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods. American Journal of Clinical Nutrition. 1997.
• Brand-Miller J et al. University of Sydney Glycemic Index Research Service.
• Ludwig DS. The Glycemic Index: Physiological Mechanisms Relating to Obesity, Diabetes, and Cardiovascular Disease. JAMA.
• Willett W. Eat, Drink, and Be Healthy. Harvard T.H. Chan School of Public Health.
• American Diabetes Association – Nutrition Recommendations.
• Holt SH, Brand-Miller JC et al. (1997). An insulin index of foods. AJCN. https://pubmed.ncbi.nlm.nih.gov/9356547/
• Ludwig DS. (2002). The glycemic index: physiological mechanisms. JAMA.
• Bell KJ et al. (2011). The insulin index of foods: Applications for diabetes care. Diabetes Care.
• Harvard Health Publishing. https://www.health.harvard.edu