# Video research-update insert: The Carbohydrate–Insulin Model of Obesity

Editorial script and storyboard insert, 5 October 2026. No rendered video. Read alongside the original review; no new grade is announced.

## Narration

Diet interventions can change insulin, expenditure and intake, but several predictions of the broad causal model fail in particular controlled settings. Adaptation, diet order, food properties and expenditure measurement remain material sources of disagreement.

In the 1999 study, high-glycemic-index meals increased subsequent voluntary intake in the tested setting. Acute meal effects do not establish chronic obesity initiation. [P10049982]

In the 2018 study, lower carbohydrate intake increased reported expenditure after weight loss. Outpatient adherence and expenditure-estimation assumptions need scrutiny; correction notice retained. [P30429127]

In the 2025 study, glucose/insulin responses differed, while hunger and individual intake relations gave little model support. Acute healthy-adult responses do not test weeks-long adaptation in common obesity. [P40043690]

The next discriminating question is: Do adaptation and order explain conflicting intake effects? Carryover, gut adaptation, fibre or food mass may dominate short crossover contrasts. Longer randomized feeding with washout or parallel arms, prespecified adaptation windows and intake endpoints; match food properties.

The timeline shows selected changes in evidence, not inevitable progress or proof of a single cause. The review’s archived grade remains unchanged; the depth of source reading is documented in the update.

## Storyboard and source locks

| Insert | Visual | Narration anchor | Sources |
|---|---|---|---|
| Opening | Claim and bounded update statement | First paragraph | Review claim and source ledger |
| Timeline 1999 | Dated study card with design, result and limit | High-glycemic-index meals increased subsequent voluntary intake in the tested setting. | [P10049982](https://pubmed.ncbi.nlm.nih.gov/10049982/) |
| Timeline 2018 | Dated study card with design, result and limit | Lower carbohydrate intake increased reported expenditure after weight loss. | [P30429127](https://pubmed.ncbi.nlm.nih.gov/30429127/) |
| Timeline 2025 | Dated study card with design, result and limit | Glucose/insulin responses differed, while hunger and individual intake relations gave little model support. | [P40043690](https://pubmed.ncbi.nlm.nih.gov/40043690/) |
| G1 | Question → competing explanation → discriminating test | Do adaptation and order explain conflicting intake effects? | [P27385608](https://pubmed.ncbi.nlm.nih.gov/27385608/), [P33479499](https://pubmed.ncbi.nlm.nih.gov/33479499/), [P39163976](https://pubmed.ncbi.nlm.nih.gov/39163976/), [P40043690](https://pubmed.ncbi.nlm.nih.gov/40043690/) |
| G2 | Question → competing explanation → discriminating test | Is an expenditure advantage reproducible across methods? | [P27385608](https://pubmed.ncbi.nlm.nih.gov/27385608/), [P30429127](https://pubmed.ncbi.nlm.nih.gov/30429127/) |
| G3 | Question → competing explanation → discriminating test | Does insulin–glucagon change mediate hunger or adiposity? | [P10049982](https://pubmed.ncbi.nlm.nih.gov/10049982/), [P26278052](https://pubmed.ncbi.nlm.nih.gov/26278052/), [P40043690](https://pubmed.ncbi.nlm.nih.gov/40043690/) |
| G4 | Question → competing explanation → discriminating test | Which phenotype benefits, over what time scale? | [P30429127](https://pubmed.ncbi.nlm.nih.gov/30429127/), [P29466592](https://pubmed.ncbi.nlm.nih.gov/29466592/), [P33479499](https://pubmed.ncbi.nlm.nih.gov/33479499/) |

## Editorial constraints

- Use the primary-source links shown above and keep the inference limit on screen with each milestone.
- Do not narrate an abstract check as complete-paper examination, a model result as human proof, or an unresolved inference as absence of all research.
- Preserve trial endpoint hierarchy, cohort reuse, correction notices and online/issue dates.
- Use original graphics made from this ledger. Publisher figure imagery has not been cleared or supplied for video reuse.
- Confirm any change in verdict through a separate documented HSEF review; this insert makes none.