Cornflakes
One of the highest-GI breakfast foods; almost no fiber to slow it down.
FatTonic Facts
Cornflakes · per serving 1 cup (30g)
Poor · works against fat-burning
| Factor | Amount | Points |
|---|---|---|
| Start | 100.0 | |
| Glycemic load | 20 | −44.0 |
| Sugar (g) | 3 | −2.4 |
| Processing | ultra-processed | −24.0 |
| Fiber (g) | 1 | +1.6 |
| Protein (g) | 2 | +1.4 |
| Glycemic index | 81 | |
| Carbs (g) | 26 | |
| Fat (g) | 0 |
Score model v1
Nutrients: USDA FoodData Central, record 174648 (Cereals ready-to-eat, RALSTON Corn Flakes), public domain, checked 2 Oct 2026.
Glycemic index: 81, the table’s own mean of five studies (Table A1 p. 11 of Atkinson et al., International Tables of Glycemic Index and Glycemic Load Values: 2008): no. 321 Cornflakes (China) 74; no. 322 Cornflakes™ (Kellogg's, Australia) 77; no. 323 Cornflakes (China) 79; no. 324 Cornflakes™ (Kellogg's Inc., Canada) 80; no. 325 Cornflakes (Kellogg's, UK) 93. Note: Crunchy Nut (326), Frosties (331) and cornflakes eaten with milk (452) are other foods and are not counted. Opened 28 Oct 2026; the 2021 edition could not be opened.
Per 100 g (USDA record; serving 30 g): carbs 88, sugar 7.8, fiber 2.7, protein 5.9, fat 0.9 g.
What this means for fat-burning
Why this score: glycemic load 20 set it, −44.0 points. Source: USDA FoodData Central, FDC 174648.
Being ultra-processed, it is also easy to overeat.
See how your whole day scores — free Metabolic Score →This food and 199 more, scored on your phone.
Among the 200 rated foods
Cornflakes scores 33, rated Poor. It scores higher than 12% of the 200 rated foods.
Rated foods per band: Avoid 0–19: 11; Poor 20–39: 23; Moderate 40–59: 34; Good 60–79: 45; Excellent 80–100: 87.
Frequently asked questions
Does cornflakes spike insulin?
Glycemic load 20 for 1 cup (30g); FatTonic Score 33/100 — it works against fat-burning.
Is cornflakes good for fat loss?
Poor (33/100): cornflakes works against fat-burning.