Thread by @NutritionMadeS3

Weight Loss: Myths & Tips

(short thread summarizing studies by Kevin Hall and others and inspired by his recent hour-long talk)

video here:

portion control and other attempts to 'eat less' backfire bc we don't burn calories at a constant rate

weight loss triggers hormone changes (e.g. leptin) that cause us to a) burn less cals b) be hungrier

it's the ultimate uphill battle

this indicates that plateaus, weight yo-yo'ing and general struggles with weight loss are not a result of laziness or lack of willpower

they're built into our biology

what's weak is the approach, not the person trying it

role of leptin in weight loss reviewed here: ncbi.nlm.nih.gov/pmc/articles/P…

these (natural) struggles explain much of the frustration and desperation around weight loss and why it's a field so ripe for misinformation and marketing

'a new diet that delivers effortless weight loss' is the ultimate marketing tool

ok, back to the science

one of the most popular ideas to emerge over the last couple decades was the carbohydrate-insulin model of obesity

according to it:

*carbs/insulin CAUSE fat gain and increase appetite*

**weight loss REQUIRES cutting carbs and lowering insulin**

numerous best-selling books put forward this interesting idea

it's now been tested in significant ways. the results haven't settled the issue completely but are informative and fascinating

Kevin Hall's team put obese subjects on 2 weight loss diets (both 30% lower in calories than baseline)

in one group the cals came from fat, in the other from carbs

acc to the carb/insulin model, only cutting carbs should deliver weight loss

the low-fat group lost significantly MORE fat than the low carb group

the diff was statistically significant but small. take home msg is that both diets resulted in comparable weight loss

C-peptide levels were lower on low carb, indicating lower insulin levels (as expected)

this does not rule out the carb/insulin model

(individual studies almost never settle an issue)

but it's a significant blow

carb/insulin reduction was not necessary for fat loss. if anything cutting fat & leaving carbs worked better. the opposite of what the model predicts

full study here: pubmed.ncbi.nlm.nih.gov/26278052/

is this an isolated result?

Hall et al. pooled 32 trials on isocaloric fat/carb reduction

both energy expenditure (calories burned) and fat loss were greater with lower fat than lower carb diets

(again, diff is small. take home msg is both diets work)
ncbi.nlm.nih.gov/pmc/articles/P…

issues: most of these studies are short duration and N is small-ish. that's the tradeoff with tightly controlled metabolic ward trials

there is no such thing as a 'perfect experiment'

every approach has tradeoffs

conclusions are reached by triangulating different techniques and studies and looking at preponderance of evidence

not by doing 1 PERFECT experiment and then going home

one example of a longer study is Chris Gardner's DIETFITS

low carb vs low fat led to comparable weight loss over 12months (600+ subjects)

jamanetwork.com/journals/jama/…

ofc when you're looking at a longer study, on a free-living population, you have more questions regarding adherence (see 'no perfect experiment' comment above)

the National Lipid Assoc. led a comprehensive review of the literature in 2019 and concluded that

"Low- and very-low-carbohydrate diets are not superior to other weight loss diets"

lipidjournal.com/article/S1933-…

ok so low carb and low fat seem comparable for fat loss, at least in very controlled isocaloric conditions

but in real life we don't have an investigator telling us when to stop eating

maybe cutting carbs doesn't burn more calories but makes us feel fuller so we eat less??

Kevin Hall's recent preprint (due diligence, let's await peer-review) looked at this question

subjects fed ad lib (aka 'all you can eat buffet') ate 700 cals/d more on low carb than low fat and lost less fat

osf.io/preprints/nutr…

what does this all mean?

cutting carbs or fat can lead to weight loss. cutting any form of calories can, as long as people can stick with it (*adherence* is the crux)

can carbs/insulin play a more direct role in fat gain and appetite in specific contexts? sure. it's possible

available evidence indicates carbs/insulin are not a major player for weight loss. but maybe more nuance will be uncovered in the future

since any form of calorie reduction seems to work if adhered to, *personal preference* is likely to be an important factor

also, individual metabolic variation very possible (although: DIETFITS found no effect of genotype)

some people may do better on low carb, others on low fat, others on intermittent fasting (or combos thereof)

if you lean toward the low carb option, bear in mind it can be done without restricting fiber or loading up on saturated fat

a ketogenic diet that delivers weight loss while lowering LDL-C, ApoB and triglycerides:

pubmed.ncbi.nlm.nih.gov/19506174/

One take home msg from all this is that macronutrients (fat/carbs/etc) are probably not crucial for weight loss (unlike what 99% of marketing will have you believe)

then what IS?

ultraprocessed foods seem to be

they can lead to more calories eaten and more fat gained even if macronutrients are matched

pubmed.ncbi.nlm.nih.gov/31105044/

calorie density may play a role. fiber. microbiome. etc

shooting for unprocessed, whole foods with low calorie density and a good amount of fiber is a good long-term bet for weight and health alike

additional factors:

- sleep affects metabolism and appetite. harder to lose fat if sleep deprived

- weight vs fat loss. losing water weight or muscle looks good on the scale but it's not what you want. keep adequate protein intake and consider a weights workout

geez and I said 'short thread'... got out of hand 😁

peace