Starting a sample of 2023 papers with a porcine review:
“Epigenetic programing predisposes pigs to insulin insensitivity, but pigs seem to sense this insensitivity and consequently eat less, preventing obesity. Pigs naturally prefer to eat small breakfasts and large dinners.
Deviating from this eating pattern or providing diets with a high glycemic burden can trigger obesity; however, pigs will restrict food intake to prevent serious obesity. In practice, problems with obesity are rarely seen, even when pigs are fed poorly timed diets similar to junk food, likely because swine diets are balanced for every nutrient.
Feeding pigs diets deficient in micronutrients does trigger obesity. For humans, several micronutrient requirements have not been set officially, and diets optimized for all micronutrients are rarely provided.
Although we could debate whether this is a cause or effect, the above data on hyper-processed diets fed to pigs would indicate that it is causative. Pigs were fed a diet which included ‘human-targeted junk food’ but was adequate in phosphate, and they experienced no issues.
Controlled human studies are generally conducted with very small populations of subjects for very short durations, as emotions come into play. Humans are hard to persuade to follow a boring diet, especially over a longer period of time, and humans are easily tempted to deviate from a protocol if peer pressure or desires are high.
Even worse, in survey type experiments, people are asked what they ate for the past one or several days, and these data may well be subsequently extrapolated to patterns of behavior and then correlated with developments in health. Recalling what and especially how much a person ate yesterday is already a challenge for many, confounded even further by the desire not to include items that may be considered less acceptable.
On the swine side, knowledge on nutrient yield of foods and nutrient requirement appears further advanced, and controlled feeding trials are much easier to perform. Borrowing pig data is arguably much closer to the truth for humans than having no data at all.”
https://onlinelibrary.wiley.com/doi/10.1002/advs.202205346 “Eat like a Pig to Combat Obesity”
One fish in the gullet, another soon on its way