Same recipe, same sugar, one extra machine: this milk chocolate sent insulin up less

We usually judge a food by what's in it: grams of sugar, fat and protein on the label. A small trial published in Food Science & Nutrition on 30 September 2026 asks whether the same ingredients, put together a different way, land differently in the body. The researchers work at the research institute of Morinaga, a Japanese confectionery company, which also paid for the study and made the chocolate.

They made two milk chocolates with exactly the same recipe: 33.55% sugar, 6.6% cocoa mass, 24.75% whole milk powder, 11% skim milk powder, 24% cocoa butter equivalent and a pinch of lecithin. For one of them, the sugar, the cocoa mass and part of the whole milk powder (about 55% of the recipe) first went through a twin-screw extruder, the kind of machine used to make puffed snacks and breakfast cereals. Inside, the mix was kneaded at up to 95°C and forced out through a 13 mm hole at about 105°C, then ground and turned into chocolate in the usual way. Lab tests found the two bars matched on nutrients: 33.5 g of sucrose per 100 g in both, 11.1 against 11.3 g of protein, 33.6 against 34.1 g of fat.

Eighteen healthy Japanese men aged 20 to 60 (average 48.7 years, average BMI 22.5) came in after a 12-hour fast on two mornings at least a week apart in February 2025. Each time they ate 20 small pieces, 76 grams in all, within five minutes, without knowing which chocolate it was; the staff didn't know either. Blood was taken seven times over three hours. Thirty minutes in, insulin was about 23% lower after the extruded chocolate (20.6 against 26.8 μU/mL), and the total insulin response stayed significantly smaller at every point checked up to two hours. Blood glucose rose less too, by 17.8 against 25.1 mg/dL above fasting at 45 minutes, but that gap fell short of statistical significance. Blood fats (triglycerides) were lower at 30 and 45 minutes, and at the two-hour mark the men rated themselves fuller after the extruded bar. In a test tube with simulated saliva and stomach fluid, less sugar dissolved out of the extruded chocolate in the first 5 and 15 minutes, which the authors think explains the slower response: the extruder may lock some of the sugar into a structure that takes longer to break up.

It is an interesting idea, and a careful design: the same people ate both bars, so differences between people cancel out. But it is one study of 18 lean, middle-aged men after a single portion, run and funded by a company that makes chocolate. There were no women, nobody with diabetes or prediabetes, and no test of what happens when the chocolate is eaten every day, with a meal, or in smaller amounts. Fasting triglycerides happened to be higher before the extruded bar (111 against 95 mg/dL, not a significant difference), and the hormone GLP-1, which helps control appetite, wasn't measured. The full data are available only on request. What the study does show is that processing is not just a label word: how a food is made can change how quickly its sugar reaches the blood, even when the nutrition panel doesn't change at all.