Should national nutrition policy target "Ultra-Processed Foods" (UPF) as many advocate?

I consider concerns in a @NEJM Perspective

Like 'The Emperor's New Clothes'

👉We're rolling out a red carpet, but the evidence is threadbare!

LINK:

1/21 🧵👇 nejm.org/doi/full/10.10… Our food system is BROKEN. To prevent chronic disease we must fix the food supply.

But focusing on UPF ("Nova" group 4) could cause more harm than good, eg

- Demonize healthy food
- Endorse unhealthy food
- Confuse regulators
- Burden public
- Invite industry manipulation

2/21

CARB Kerfuffle

Our new analysis of a famous trial (DIETFITS) finds that reducing processed carbs drove weight loss compared to fat/calorie intake

Critics claim we don't explain "all or most" wt loss, so our findings can be dismissed

Let's consider
1/13
doi.org/10.1016/j.ajcn… In Figure 3:

👉Reduction in glycemic load (GL, think processed carbs) predicted weight loss, with strong statistical confidence

👉Fat intake was unrelated

However, there is a lot of variability (the individual data points)

Does this variability undermine our findings?
2/13

Digging into DIETFITS!

In this major trial from 2018, weight loss did not differ on a low-carb vs low-fat #diet

Does this disprove carb-insulin model of #obesity?

In a reanalysis my coauthors and I offer a different interpretation

Open Access Link doi.org/10.1016/j.ajcn…
1/10 One BIG design issue:

👉Both diet groups were told to eat less processed grains and sugar.

👉Notably, intake of carbs and glycemic load went down in BOTH groups. (The opposite usually happens on low-fat diets).

Could this have driven the weight loss in BOTH GROUPS?

2/10

What do GLP-1 weight loss drugs reveal about the cause of obesity?

GLP-1 has actions in brain and reduces food intake. Some argue this:

Supports Energy Balance Model
(overeating CAUSES ⬆️ body fat)

Opposes Carbohydrate-Insulin Model
(⬆️ body fat CAUSES overeating)

Thread
1/5 HOWEVER brain controls metabolism, not just food intake.

👉Vagal innervation GI tract, liver, pancreas
👉Autonomic innervation of adipose tissue, etc

Many so called “hunger” and “satiety” hormones affect body composition independently of food intake

doi.org/10.1038/s41430…
2/5

Critics of the Carbohydrate-Insulin Model built a new Energy Balance Model of obesity.

My 15 coauthors and I have a few thoughts about it. @ejcneditor @SpringerNature #CarbInsulinModel

New review open access at this link 👇👇👇

doi.org/10.1038/s41430…
Thread 1/16 Models Have Opposing Views of Cause & Effect

👉Energy Balance Model: overeating CAUSES obesity

👉Carb-Insulin Model: process of getting fat (energy partitioning) CAUSES overeating

Consider adolescent growth spurt: Overeating is a consequence, not cause, of rapid growth

2/16

To paraphrase Mark Twain:

Reports of the death of the Carbohydrate-Insulin Model have been exaggerated.

👉17-author review @AJCNutrition
👉Deep dive on obesity mechanisms
👉Numerous hypotheses to guide constructive debate

Free text👉 doi.org/10.1093/ajcn/n…

Thread (0/12)👇 1/12
The simplicity of the Energy Balance Model belies a tautology.

Weight gain can occur only with a positive energy balance, as fever can occur only if the body generates more heat than it dissipates.

👉These reiterations of physics provide no information on biological causes