White bread, rice and pasta are often singled out for their high glycemic index (GI). Lacking fiber, their carbohydrates are quickly transformed into glucose, causing insulin spikes that promote fat storage and the risk of diabetes.
The secret of “resistant starch”: when the cold transforms the sugar
However, a simple switch to cold weather could change things via a process called retrogradation.
Under the effect of cold (ideally 12 to 24 hours in the freezer), the starch molecules realign to form robust crystal structures.
“Resistant starch slows the absorption of other carbohydrates into the bloodstream. As fewer carbohydrates are absorbed, the impact on blood sugar is lessened, reducing glucose and insulin spikes” explains Avery Zenker, dietitian, in an article for the Daily Mail.
Benefits reminiscent of the effects of slimming medications
This transformation does not just smooth the blood sugar curve. Resistant starch acts similarly to fiber. It is not digested in the small intestine and ends up feeding the good bacteria in the colon. With surprising effects:
- Long-lasting satiety: It would stimulate the production of GLP-1, an intestinal hormone which slows digestion (the same mechanism imitated by certain weight-loss drugs);
- Weight loss: A 2024 study published in Nature Metabolism showed that consumption of resistant starch promoted greater weight loss compared to a control group;
- Increased effectiveness: Toasting the bread after defrosting would further reduce the glycemic response.
Why should this tip be put into perspective?
If science confirms the formation of resistant starch, Pauline Pied, dietician, invites us to take a step back. According to her, this data is interesting in isolation, but loses its relevance once on the plate.
“These tips are only of interest if you consume the food alone. However, as part of a balanced meal, we do not eat simple plates of pasta or plain bread. We add fiber, lipids and proteins. specifies Pauline Pied.
The expert recalls that the presence of other nutrients naturally modifies digestion:
“The fiber in vegetables and good fats already lower the overall glycemic index. The glycemic load of the complete meal therefore remains low. For a diabetic person or someone wishing to lose weight, the secret lies more in the balance of the meal than in the storage temperature of the bread.”
Caution and moderation: the real instructions
Should we therefore abandon the idea? Not necessarily, but it should not be seen as an unlimited “license to eat”. Putting the bread in the freezer increases the resistant starch level from 1% to around 3%. It’s a bonus, but not a calorie revolution.
“It is important to emphasize that the benefit of resistant starch remains modest. Portion management therefore remains essential. recalls Avery Zenker.
For Pauline Pied, the essential is elsewhere. “In daily practice, looking at data for a food consumed alone does not really make sense. The important thing is all the foods ingested. If your meal contains enough vegetables and protein, the method of freezing your bread becomes entirely secondary.”