Is the insulin index the same as the glycemic index?

No. The Glycemic Index (GI) measures how much a food raises blood glucose, using a portion containing 50 g of digestible carbohydrate. The Food Insulin Index measures how much a food raises blood insulin, using a 1,000 kJ (239 kcal) portion. The key difference is that II captures the insulin response from all macronutrients — protein and fat also stimulate insulin — while GI only measures carbohydrate effects on glucose.

Can a food have a low glycemic index but a high insulin index?

Yes, and this is one of the most important insights from FII research. Lean beef and fish have essentially no glycemic index (they contain no digestible carbohydrates), yet they produce a meaningful insulin response due to insulinogenic amino acids. Conversely, some high-fat bakery products may have a lower GI (fat slows glucose absorption) but a higher insulin index because refined carbohydrates combined with fat trigger a disproportionate insulin response.

Should people with diabetes use the insulin index?

The II can be a valuable supplementary tool for people with both type 1 and type 2 diabetes. For type 1 diabetes, it can help refine meal-time insulin dosing beyond carbohydrate counting alone — particularly for protein- and fat-heavy meals. For type 2 diabetes and insulin resistance, choosing low-FII foods may help reduce the burden on the pancreas and improve insulin sensitivity over time. Always implement dietary changes with the guidance of your healthcare team.

What is the best low-insulin-index breakfast?

Based on the available II data, one of the lowest-insulin-index breakfast combinations is eggs cooked in olive oil or butter, paired with steel-cut oats or all-bran cereal. Eggs score around 31, while oatmeal scores around 40. Adding a small handful of peanuts or almonds lowers the overall meal insulin demand further. Avoid fruit juice, sweetened cereals, and flavored low-fat yogurts at breakfast — these score significantly higher on the insulin index.

Why do potatoes have a higher insulin index than white bread?

Boiled potatoes score approximately 121 on the insulin index — higher than white bread (100). Potato starch is highly digestible when cooked, leading to rapid glucose release and a strong insulin response. White bread, while refined, contains some protein from wheat gluten and a different starch structure that slightly moderates the response. You can lower the insulin impact of potatoes by cooling them after cooking (which converts some starch to resistant starch) or by eating them with protein and fat.

Is a low-insulin-index diet the same as a low-carb diet?

Not exactly. While reducing high-GI refined carbohydrates does lower insulin demand, the II reveals a more nuanced picture. Pasta scores low despite being carbohydrate-rich. Legumes and oatmeal score moderately despite containing substantial carbohydrates. Conversely, lean meats and fish — carbohydrate-free foods — still produce a meaningful insulin response. A low-II diet focuses on the quality and combination of foods, not simply on eliminating carbohydrates.

Glycemic Index vs Insulin Index: What Matters More for Weight Loss? | InsulinGuru

Weight Loss

Glycemic Index vs. Insulin Index: What Matters More for Weight Loss?

Both tools measure how your body responds to food — but they ask very different questions. Understanding the difference could change how you eat for fat loss.

InsulinGuru Editorial Team

Updated April 2025

| 8 min read | Medically reviewed

Why This Question Matters for Fat Loss

If you've spent any time researching weight loss through diet, you've probably heard of the glycemic index. It's been the go-to framework for decades — printed on food packaging, recommended by dietitians, and built into popular eating plans like the Zone Diet and South Beach.

But there's a newer, more complete measurement that nutrition researchers have been studying since the 1990s: the food insulin index (FII), also called the insulin index. And it tells a fundamentally different story about how food affects your ability to lose fat.

Both tools give you numbers. Both can guide your food choices. But they measure different things — and for the specific goal of reducing body fat, that difference is significant.

Key insight

Insulin is the master regulator of fat storage. When insulin is elevated, your body cannot access stored fat for energy. Understanding which foods drive insulin — not just blood sugar — is the more direct path to fat loss.

What Is the Glycemic Index?

The glycemic index (GI) was developed at the University of Toronto in the early 1980s by Dr. David Jenkins and colleagues. It measures how fast the carbohydrates in a food raise blood glucose levels compared to pure glucose (scored at 100).

How GI is measured

Subjects eat a portion of food containing 50g of digestible carbohydrates. Blood glucose is tested over 2 hours. The area under the blood glucose curve is compared to that of pure glucose.

≤55Low GI

56–69Medium GI

≥70High GI

For many years, GI was a useful shorthand: avoid white bread, white rice, and sugary drinks; prefer whole grains, legumes, and most vegetables. This advice isn't wrong — but it's incomplete.

The limits of glycemic index

The GI has a critical blind spot: it only applies to carbohydrate-containing foods. Meat, fish, eggs, and most cheeses have a GI of zero by definition — because they contain no digestible carbs. But this doesn't mean they have zero effect on insulin. Far from it.

Additionally, GI ignores portion size. Watermelon has a high GI (around 72), but a typical serving contains very little sugar in absolute terms. The related concept of glycemic load (GL) was introduced to address this — but GL still doesn't capture the full insulin picture.

What Is the Insulin Index?

The food insulin index (FII) was developed by Dr. Susanna Holt and colleagues at the University of Sydney in the 1990s. Instead of measuring blood glucose, it directly measures the insulin response that a food produces over two hours.

How FII is measured

Subjects eat a portion of food providing 1,000 kJ (240 kcal) of energy. Insulin is tested over 2 hours. The area under the insulin curve is compared to that of white bread (reference = 100).

<40Low II

40–70Moderate II

>70High II

Because insulin secretion is driven by all macronutrients — not just carbohydrates — the FII works for every food category. It captures the insulinogenic effects of protein (especially whey), certain fats, and the combined impact of a mixed meal.

Insulin Index of common foods Source: Holt et al., 1997; University of Sydney FII database

Food	GI	Insulin Index (FII)
Eggs	0	31
Beef (lean)	0	51
Plain yogurt (full fat)	36	62
Brown rice	55	62
White bread	70	100
Skim milk	32	98
Jelly beans	78	117
Lentils	29	58
Almonds	0	20
Apples	38	59

⚠️ Surprising finding

Skim milk has a GI of just 32 — well within the "low" range — yet its insulin index is 98, nearly identical to white bread. This is driven by the whey protein content and the unique insulinogenic effect of dairy, and would never be captured by GI alone.

Insulin Index vs. Glycemic Index: Why You Need Both

The glycemic index (GI) measures how quickly a carbohydrate-containing food raises blood glucose. It's been a popular tool for decades. But it has a significant blind spot: it only measures blood sugar, not insulin — and blood sugar and insulin don't always move in lockstep.

🩸 Glycemic Index (GI)

Measures blood glucose response
Only relevant for carbohydrate-containing foods
Ignores protein- and fat-driven insulin
Doesn't account for portion size
Developed in the 1980s (University of Toronto)

More Complete

💉 Food Insulin Index (FII)

Measures insulin secretion response
Works for all foods — including meat, dairy, eggs
Captures combined macronutrient effects
Standardized to equal energy loads
Validated in multiple clinical studies

A striking example: beef and fish have a glycemic index of zero (no carbs = no blood sugar spike), but they still produce an insulin response of around 30–50 on the FII scale. Meanwhile, plain yogurt has a low GI but a surprisingly high insulin index — driven by dairy proteins and the insulinogenic effect of whey.

⚠️ Important nuance

This does not mean you should avoid lean protein or yogurt. The absolute insulin response matters — not just the index score. A food with a moderate FII eaten in a small portion may produce far less total insulin than a low-FII food eaten in a large quantity.

This nuance is what makes the II so valuable for anyone trying to lose weight or manage it long-term. Two foods with identical calorie counts and identical glycemic index scores can produce very different insulin responses — and that difference matters enormously to your fat metabolism.

Which Index Matters More for Weight Loss?

"Insulin is the primary regulator of fat storage in adipose tissue. As long as insulin is elevated, lipolysis — the breakdown of stored fat — is suppressed. Reducing the foods and meals that drive the greatest insulin spikes is a direct and rational strategy for facilitating fat oxidation."

Dr. R. David Feinman

Professor of Biochemistry, SUNY Downstate Medical Center

The short answer: for fat loss specifically, the insulin index is the more direct and relevant metric. Here's why.

Fat burning (lipolysis) is controlled primarily by insulin. When blood insulin is high, your fat cells are in "storage mode" — they actively take up fatty acids and refuse to release them. When insulin is low, fat cells open up and release stored fatty acids to be burned for energy. This is basic physiology, and it's why many low-carbohydrate and ketogenic diets work so well for fat loss — they are, at their core, low-insulin diets.

The GI is useful for predicting blood sugar spikes — and blood sugar spikes do drive insulin spikes, especially in people with insulin resistance. But it misses a large part of the picture: all the insulin that is secreted independently of blood glucose, in response to protein, dairy, and mixed meal effects.

Research comparing GI-based dietary advice to FII-based advice has consistently found that using the insulin index leads to better insulin management — particularly for people with type 2 diabetes, prediabetes, or metabolic syndrome, where hyperinsulinemia is a central driver of weight gain.

Our Verdict

The insulin index is the more powerful tool for weight loss because it directly measures what matters: how much insulin a food provokes. GI is a useful but incomplete shortcut that misses the insulin cost of protein, dairy, and mixed meals.

However, GI remains valuable for quickly identifying high-carbohydrate foods that cause blood sugar spikes. The smartest approach is to use both: minimize high-GI foods and minimize high-II foods. Where they diverge, trust the insulin index.

How to Use Both Indices in Practice

You don't need to obsess over numbers — but understanding the patterns that each index reveals will make your food choices much more strategic.

The rules that hold true for both indices

There is significant overlap between low-GI and low-II eating. Foods that tend to score well on both indices include:

Most non-starchy vegetables (broccoli, leafy greens, zucchini, peppers)
Whole eggs and fatty fish
Nuts, seeds, and avocado
Legumes (beans, lentils, chickpeas) — low GI and moderate II
Berries and most whole fruits

Where GI and insulin index diverge — and what to do

The disagreements between the two indices are the most actionable insights:

When GI and FII give different signals

Food	GI signal	FII signal	Recommendation
Skim milk	Low ✓	High ✗	Limit for fat loss; prefer full-fat dairy in smaller amounts
Lean chicken breast	Zero ✓	Moderate ~	Fine in normal portions; don't avoid it, but don't overdo it
Pasta (al dente)	Medium ~	Medium ~	Moderate portions; pair with fat and protein to slow digestion
Watermelon	High ✗	Low ✓	Fine in typical serving sizes — GI is misleading here

A simple framework to follow

1Eliminate or minimize high-GI carbohydrates (white bread, sugary drinks, processed cereals) — they raise both blood sugar and insulin fast.
2Reduce high-FII foods that GI misses — particularly large amounts of low-fat dairy and highly processed protein products like protein bars and shakes made with whey isolate.
3Build your meals around whole proteins, fibrous vegetables, and healthy fats — the category of foods that scores well on both systems.
4Pay attention to total insulin load of your meal, not just individual food scores. Combining a moderate-FII food with a high-FII food and a high-GI starch creates a far larger insulin response than any single food would suggest.

Sample Low-Insulin Day of Eating

Here's what a practical, low-insulin-load day looks like — designed to keep both GI and FII low across all three meals.

Breakfast

Eggs & Avocado

2–3 whole eggs, scrambled in olive oil. ½ avocado. Handful of cherry tomatoes. Black coffee or green tea.

FII: Low

Lunch

Salmon & Greens Bowl

150g baked salmon. Large bed of mixed greens, cucumber, and olives. Lemon-olive oil dressing. Small portion of lentils.

FII: Low–Moderate

Dinner

Beef Stir-Fry

150g lean beef strips. Broccoli, bell peppers, snap peas. Coconut aminos. Small portion of brown rice or skip for lower II.

FII: Moderate

✓ Why this works

This day avoids the three biggest insulin drivers: high-GI refined carbohydrates, large amounts of low-fat dairy, and frequent eating (which keeps insulin chronically elevated). It's not zero-carb — it uses legumes and vegetables — but every carbohydrate source is paired with fiber, fat, or protein to blunt the insulin response.

Frequently Asked Questions

Can I just use the glycemic index and ignore the insulin index? +

For most people eating a varied diet that includes dairy and significant amounts of protein, relying on GI alone will miss a substantial portion of your daily insulin load. The insulin index adds the most value for people who already eat low-GI but still struggle to lose fat — it often reveals hidden insulin-driving foods like low-fat yogurt, whey protein, or processed "health" foods.

Does this mean I should stop eating protein to lower my insulin? +

No. Protein causes a moderate insulin response, but it also causes a proportional glucagon response — which counterbalances the insulin effect and keeps blood glucose stable. The net metabolic effect of eating protein is very different from eating sugar, even if the insulin numbers look similar. Prioritize protein; just avoid excessive amounts of highly processed, rapidly absorbed protein like whey isolate shakes.

Is the insulin index the same as the insulin load? +

No. The insulin index (FII) is a per-calorie score for a specific food. The insulin load is a broader concept that accounts for the total insulin-stimulating potential of a meal or a full day of eating, taking into account portion sizes. Both are useful — the FII helps you choose better individual foods, while insulin load helps you evaluate your overall dietary pattern.

Is the food insulin index well-researched? +

The FII database is smaller than the GI database — fewer foods have been formally tested. It has been validated in multiple clinical studies, particularly in populations with type 2 diabetes and obesity, but it is still less widely used in clinical practice than GI. The core finding — that insulin response varies substantially between foods even when carbohydrate content is identical — is well-supported in the scientific literature.

Do I need to count numbers to benefit from this approach? +

Not at all. The practical patterns that emerge from both indices are intuitive: eat whole, minimally processed foods; prioritize fibrous vegetables, whole proteins, and natural fats; minimize refined grains, sugary foods, and large amounts of low-fat dairy. Most people get 80% of the benefit without ever memorizing a single score.

Key Takeaways

📊

GI only measures carbohydrate foods Proteins and fats have a GI of zero — but they still stimulate insulin secretion, which GI completely ignores.

💉

Insulin index covers all foods The FII measures the actual insulin response from any food — including meat, dairy, eggs, and mixed meals.

🔥

Insulin blocks fat burning High insulin suppresses lipolysis. Reducing dietary insulin drivers — as revealed by the FII — creates conditions for fat loss.

🥗

Use both, prioritize FII Avoid high-GI foods for blood sugar stability; use FII for a more complete view of your daily insulin load and fat loss potential.

References & Further Reading

Holt SH, Miller JC, Petocz P. An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods. Am J Clin Nutr. 1997;66(5):1264–1276.
Jenkins DJ, Wolever TM, Taylor RH, et al. Glycemic index of foods: a physiological basis for carbohydrate exchange. Am J Clin Nutr. 1981;34(3):362–366.
Brand-Miller JC, Holt SHA, Pawlak DB, McMillan J. Glycemic index and obesity. Am J Clin Nutr. 2002;76(1):281S–285S.
Feinman RD, Pogozelski WK, Astrup A, et al. Dietary carbohydrate restriction as the first approach in diabetes management. Nutrition. 2015;31(1):1–13.
Nuttall FQ, Gannon MC. Plasma glucose and insulin response to macronutrients in nondiabetic and NIDDM subjects. Diabetes Care. 1991;14(9):824–838.
Bao J, de Jong V, Atkinson F, Petocz P, Brand-Miller JC. Food insulin index: physiologic basis for predicting insulin demand from mixed meals. Am J Clin Nutr. 2009;90(4):986–992.