HoldsUp

Daniel Lieberman

Harvard University

Daniel Lieberman is a professor of human evolutionary biology, paleoanthropologist, and author at Harvard. His published research focuses on the biomechanics and energetics of human physical activity, including studies on running kinematics, footwear, and metabolic rates. He also investigates the physiological and metabolic impacts of exercise, such as energy expenditure, myokine secretion, and disease prevention.

67 claims checked on air: 5 context 5 contradicted 7 overstated 41 supported 9 unverified

What they said on air - contradicted

1 citing their own research

0:08:16contradictedmoderateHarvard Professor: “I Tried Every Diet. This Is By Far The W

Red meat contains the sialic acid Neu5Gc, which triggers an inflammatory response in all humans due to CMAH gene inactivation.

"red meat has a particular kind of glycoprotein called Neu5Gc. I mean, that doesn't really matter with the name, but it turns out that humans have an inflammatory response to that. All humans All humans, there's a gene called CMAH which causes us to to transform one glycoprotein into another kind, and that makes us have a response to any red meat." (said at 0:08:16)

The speaker bundles two claims. The first assertion—that red meat contains the sialic acid Neu5Gc, which is metabolically incorporated into human tissues and elicits an immune/inflammatory response (xenosialitis) due to universally circulating anti-Neu5Gc antibodies in all humans—is supported by evidence. However, the speaker's genetic mechanism is stated backwards: humans do not have an active CMAH gene that transforms glycoproteins. Rather, humans possess an evolutionary loss-of-function (inactivating) deletion in the CMAH (cytidine monophosphate-N-acetylneuraminic acid hydroxylase) gene, which normally converts CMP-Neu5Ac to CMP-Neu5Gc in other mammals. It is the complete loss/inactivation of CMAH in humans that prevents endogenous Neu5Gc synthesis and causes dietary Neu5Gc to be recognized as a foreign xeno-antigen.

0:15:45contradictedhighHarvard Professor: “I Tried Every Diet. This Is By Far The W

The human body cannot store excess protein, converting surplus intake into fat.

"the body can't store extra protein. If you eat more protein than your body can use, you can't store it. So what do you do? You turn it into turn it into fat." (said at 0:15:45)

While the human body lacks a dedicated, specialized storage organ for amino acids (unlike adipose tissue for lipids or glycogen for glucose), excess dietary protein is not simply converted into body fat. In controlled metabolic ward overfeeding trials, surplus dietary protein primarily increases protein oxidation, thermogenesis (energy expenditure), and lean body mass accretion, rather than body fat. In an 8-week randomized controlled inpatient trial by Bray et al. (2012), overfeeding healthy adults with 5%, 15%, or 25% protein diets resulted in similar increases in body fat across all groups (driven by total caloric surplus), but participants consuming higher protein diets gained significantly more lean body mass and experienced increased resting and total energy expenditure without any increase in body fat storage attributable to protein.

1:34:04contradictedhighHarvard Professor: “I Tried Every Diet. This Is By Far The W

Milk is the only natural food not requiring modern processing or stores that contains high levels of both fat and sugar.

"Can you name a natural food that's high in both sugar and fat that you can get without stores? In fact, there's only one. There's only one... Milk is rich in fat and it's rich in sugars, right? But after you wean, that's it" (said at 1:34:04)

The speaker claims that milk is the *only* natural, unprocessed food available without modern processing or stores that contains high levels of both fat and sugar. However, quantitative definitions of hyper-palatable or nutrient combinations of fat and sugar (such as >20% calories from fat and >20% calories from simple sugars) demonstrate that various unprocessed whole foods—such as milk, but also other natural, unprocessed foods like certain tropical fruits (e.g., durian, avocado, young coconut meat, or jackfruit)—naturally contain significant levels of both fat and carbohydrates/sugars without requiring industrial processing. Furthermore, human milk contains roughly 4% fat and 7% lactose (sugar), which represents a high combination of both macronutrients, but it is not unique in nature, as multiple plant and animal whole foods naturally provide combinations of fats and carbohydrates/sugars.

1:56:48contradictedmoderateHarvard Professor: “I Tried Every Diet. This Is By Far The W

Weight regained following the discontinuation of GLP-1 medications is gained almost entirely as body fat rather than lean muscle mass.

"so that's that's a concern because then when they regain the weight, they tend to gain it almost completely as fat, not as muscle. And so then in a way they're worse off." (said at 1:56:48)

There is no published trial evidence showing that weight regained after discontinuing GLP-1 receptor agonists is gained almost entirely as body fat while failing to regain lean mass, or that patients end up with a worse body composition than before treatment. In the 1-year off-treatment extension of the randomized STEP 1 trial (PMID 35441470), participants who withdrew from semaglutide 2.4 mg regained approximately two-thirds of their lost weight by week 120, but still retained a net weight reduction of 5.6% relative to baseline, while cardiometabolic risk markers reverted towards baseline rather than worsening beyond initial levels.

2:04:50contradictedhighHarvard Professor: “I Tried Every Diet. This Is By Far The W

In Mexico, when a tax was placed on soda, it was fought by companies like Coca-Cola and reversed.

"And in fact, in Mexico when they tried to put a tax on on on soda, uh it got fought by the big uh by the like Coca-Cola. Yeah. And and and and the tax was reversed." (said at 2:04:50)

While beverage companies and industry trade groups strongly lobbied against Mexico's sugar-sweetened beverage (SSB) tax, the tax was not reversed. Mexico implemented a nationwide 1-peso-per-liter excise tax on SSBs on January 1, 2014, and the policy remained in effect and continues to be enforced, leading to sustained reductions in the purchases of taxed beverages.

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