Kevin Hall Profile picture
Nutrition & metabolism scientist. Brady & Cameron’s dad. Tweets are my personal views.
Nov 27 8 tweets 3 min read
This was a fascinating meeting on UPF policies and I was happy to present some preliminary results of our ongoing RCT on mechanisms by which diets high in UPFs cause excess energy intake. Here’s a brief summary 🧵 Study participants were admitted to @NIHClinicalCntr for a month where we exposed them to 4 different food environments with 6000 kcal/d as described below and instructions to eat as much or as little as they wanted. Image
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Nov 6, 2023 10 tweets 4 min read
All weight loss interventions eventually result in a plateau, but different interventions seem to affect the timing of the plateau. What determines when the plateau occurs? I wrote a short paper about this topic and I would appreciate hearing your comments biorxiv.org/content/10.110… The weight loss plateau occurs when energy intake = expenditure. I used our validated mathematical model of human metabolism & body composition dynamics to simulate various interventions affecting energy intake and try to figure out the timing of the observed weight loss plateaus
Jun 15, 2023 10 tweets 3 min read
New preprint led by @AaronHengist just posted to @medrxivpreprint: "Imprecision nutrition? Duplicate meals result in unreliable individual glycemic responses measured by continuous glucose monitors across three dietary patterns in adults without diabetes"
medrxiv.org/content/10.110… Continuous glucose monitors (CGMs) are increasingly being used to guide personalized or "precision" diets in people without diabetes by identifying meals that result in low postprandial glucose levels for each individual. jamanetwork.com/journals/jama/…
Jun 12, 2023 7 tweets 4 min read
From the shocking title of this new @NatMetabolism paper that brain responses to nutrients were significantly different between people with & without obesity. But I don't see where the authors made any such comparisons! Rather, there seems to be an error in interpretation... Specifically, the authors elegantly showed that people without obesity have statistically significant neural responses to intragastric nutrients. Such responses weren't significant in people with obesity. But this doesn't necessarily imply there were significant group differences
May 11, 2023 8 tweets 3 min read
Happy to announce a new preprint with @AaronHengist, @CmSciarrillo, Juen Guo & Mary Walter entitled “Discordance between gut-derived appetite hormones and energy intake in humans” that we just submitted for publication.
medrxiv.org/content/10.110… Endogenous gut-derived appetite hormones (like GLP-1, GIP, ghrelin, & PYY) are often thought to play a dominant role in controlling energy intake in humans & provide theoretical basis for why some diets may help facilitate weight loss better than others. Is this true?
Apr 22, 2023 9 tweets 4 min read
In this thoughtful article, @jflier’s main criticism of the Energy Balance Model (EBM) is that “the EBM as currently elaborated does not propose approaches to explain how specific environmental influences enable known anti-obesity homeostatic defenses to be evaded” But the EBM does propose an approach to this question: study how changing food environments in specific ways alters ad libitum energy intake in people (or rodents) not trying to change their weight & study how these environmental changes affect neural circuits controlling feeding
Mar 9, 2023 5 tweets 2 min read
Fully agree with @JohnSpeakman4: “we’ve got no clue whatsoever as to whether, because there are different types [of obesity], that means there should be different solutions, or whether a [single] solution still would treat all of them.” “Subtyping people with obesity is not reliable,” said Samuel Klein,…“because there is not enough data to identify obesity subtypes and what specific treatment approaches would be most effective for individual subtypes.”
Jan 30, 2023 17 tweets 5 min read
What determines how many calories people eat during a meal? Our new study, led by Tera Fazzino @UnivOfKansas, was just published in @NatureFoodJnl & investigated the meal characteristics that influence ad libitum energy intake. nature.com/articles/s4301… We estimated how energy density (ED), hyper-palatable foods (HPFs), protein (Prot) & eating rate (ERate) affected energy intake of 2733 meals from four dietary patterns: minimally processed low-carb & low-fat as well as mixed macronutrient ultra-processed & unprocessed diets.
Jun 13, 2022 8 tweets 3 min read
I've recently been asked what I think of this new @AJCNutrition Perspective by @Dmozaffarian claiming that obesity is an unexplained epidemic: doi.org/10.1093/ajcn/n… The figure shows increasing prevalence of obesity in the USA since the turn of the 21st century but per capita daily energy availability in the food supply and energy intake calculated from self-reported food intake has not increased. Ergo energy intake does not explain obesity?
May 9, 2022 13 tweets 3 min read
New preprint led by Tera Fazzino just posted describing “A data-driven approach to quantifying meal characteristics influencing energy intake”. biorxiv.org/content/10.110… Our goal was to determine the influence of energy density (ED), hyper-palatability (%HPF), protein content (%Prot), and eating rate ERate) on ad libitum non-beverage energy intake during 2733 meals consumed by 35 inpatient adults who participated in two 28-day feeding studies.
May 6, 2022 10 tweets 4 min read
We all make mistakes, right? I hope to recognize as many as possible and correct them ASAP. In this thread I'll describe a soon to be issued formal correction to our 2014 @molpsychiatry paper on brain dopamine D2 receptor binding potential (D2BP) & obesity pubmed.ncbi.nlm.nih.gov/25199919/ I'm thankful that the main results of the study were unaffected by the error. The conclusions in the Abstract are unchanged. Eg., below left is the published brain map showing where D2BP is positively & negatively correlated with BMI. Below right is the corrected version. Whew! ImageImage
Mar 9, 2022 4 tweets 2 min read
The "new" push-pull model of obesity is being billed as a more complete model encompassing the Energy Balance Model (EBM) and the Carbohydrate Insulin Model (CIM), with the former implicitly identified as the "push model" and the latter as the "pull model". But this is inaccurate The push model "explicitly excludes metabolic effects of food that are independent of calories. That is, all calories are considered alike to the body and no macronutrient has any special calorie- independent effect on lipid storage or energy expenditure for practical purposes."
Feb 8, 2022 7 tweets 3 min read
Interesting new study: Effect of Sleep Extension on Energy Intake Among Adults With Overweight ja.ma/3rwfakG via @JAMAInternalMed. But is it valid to predict ~12 kg long-term weight loss assuming sustained sleep improvements? Probably not. Let me explain... The predicted long-term weight losses arise by assuming that the observed short-term sleep improvements and the energy intake differences are both sustained. The authors then used our 2011 mathematical model to calculate the long-term weight losses: pubmed.ncbi.nlm.nih.gov/21872751/
Feb 8, 2022 7 tweets 3 min read
Interesting new paper that describes a "push-pull" model of obesity. My interpretation is that the short-term "push-pull" at the adipose tissue is merely the usual hormonal regulation of fat storage and release already included in the Energy Balance Model. academic.oup.com/ajcn/advance-a… In other words, endocrine regulation of fat metabolism evolved to ensure that whole-body energy & fat imbalances (dictated by the hierarchy of metabolic fuel selection) are targeted mostly in the safest place for their storage (adipose) as opposed to their ectopic accumulation.
Feb 4, 2022 25 tweets 8 min read
I was honored to lead an international team of renowned obesity scientists (including @Farooqi_Lab @StephenORahilly @DrLeanneRedman @JohnSpeakman4 @deirdre_tobias) to address widespread misunderstandings about modern obesity science in @AJCNutrition: academic.oup.com/ajcn/advance-a… Increased prevalence of common obesity isn't primarily due to weak willpower, inaccurate calorie counting, hungry fat cells, or too many carbs versus fat in the diet.
Feb 2, 2022 4 tweets 2 min read
An alternative view: the vast majority of the CGM differences between diets were evident within a short time period and subsequent longer term differences, while perhaps statistically significant, aren't necessarily physiologically meaningful. Error bars help illustrate this: Image This study was admittedly a purely exploratory analysis designed to detect *any* post 2-week changes, regardless of whether such changes were meaningful. This analysis was not included in the pre-specified statistical analysis plan for the CGM data: osf.io/m6v73/
Nov 24, 2021 16 tweets 5 min read
My latest Perspective was just published by @ObesitySociety: "Energy compensation and metabolic adaptation: 'The Biggest Loser' study reinterpreted" onlinelibrary.wiley.com/doi/10.1002/ob… It's just over a decade ago that I had the crazy idea to study energy expenditure and body composition changes over time in the Biggest Loser contestants. Since we did these studies, I've had some time to reflect on their interpretation.
Oct 25, 2021 5 tweets 2 min read
"Eliminate or reformulate ultra-processed foods? Biological mechanisms matter" is my first publication with @deirdre_tobias and is now online in @Cell_Metabolism and free to access until December 14 authors.elsevier.com/a/1dzY65WXUlLI… TLDR: "...the evidence against UPFs is sufficient to recommend that those with the means and desire to replace UPFs with less processed foods should be encouraged to do so. However, the broad NOVA classification system may be too blunt to guide public health responses"
Jul 16, 2021 6 tweets 2 min read
"It's those carbohydrates that ultimately determine how much fat we accumulate" page 122, Why We Get Fat by @garytaubes The logic appears solid: Insulin promotes fat storage & inhibits it's release from adipose tissue. Eating carbs causes insulin to increase after meals. Therefore, "carbohydrate is driving insulin is driving fat" as George Cahill purportedly told @garytaubes in an interview. True!
Jul 13, 2021 5 tweets 2 min read
There's widespread misunderstanding of the energy balance model (EBM) of obesity. The EBM does NOT postulate that food intake is primarily under conscious control or that obesity is a failure of willpower and can be effectively treated by calorie counting or advice to “eat less”. The EBM postulates that the food environment & the foods we eat affect feedback control of appetite & body weight regulation mediated by a variety of hormones & other signals acting on brain regions involved in sensory processing, reward, incentive salience, habit & homeostasis.
Jul 12, 2021 4 tweets 2 min read
Just submitted a Rapid Response to @BMJNutrition entitled "Erroneous assumptions invalidate the calculated effects of reducing ultra-processed food consumption on child and adolescent obesity". I hope the full text is posted soon. Basically, there are two problems: The first involves calculating energy intake changes resulting from eliminating ultra-processed food. The authors rely on our metabolic ward study in 20 adults and make several unjustified assumptions to extrapolate to free-living children and adolescents pubmed.ncbi.nlm.nih.gov/31105044/