What we eat is making us obese and sick — but science shows solutions are within reach

Food Intelligence: The Science of How Food Both Nourishes and Harms Us Julia Belluz & Kevin Hall Avery (2025)

In 2019, Kevin Hall, a physicist turned nutrition researcher, published a landmark study¹. In it, 20 adults ate one of two diets, which were identical in nutrients and differed only in their level of processing. Participants who ate ultra-processed foods (UPFs) consumed about 500 kilocalories more per day and gained weight, whereas those on a minimally processed diet lost weight. The results offered strong evidence that many industrially produced foods can override satiety signals and drive overeating. And it made Hall one of the most influential figures in nutritional science.

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Understandably, expectations were high for his book, Food Intelligence, co-written with Canadian journalist Julia Belluz. It digs deeper into the implications of the 2019 study — that the harms of processed foods can’t be reduced to their fat, sugar or salt content alone, and that the prevalent government strategy of politely asking companies to tweak their recipes by cutting salt or sugar content, say, is unlikely to address rising obesity rates. Unfortunately, the execution only partly lives up to the promise.

In this wide-ranging primer on food science, Hall and Belluz revisit many food-related misconceptions. They debunk the idea that cutting 500 kilocalories a day reliably leads to the loss of half a kilogram a week and that “broken metabolism” explains obesity — as Hall highlighted in his role as a scientific adviser to the reality television programme The Biggest Loser, in which contestants attempt extreme weight loss.

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The authors challenge the current obsession with protein, noting that most people already consume enough through ordinary diets. They are equally dismissive of the booming supplements industry, arguing that many products lack clinical evidence or have been shown to offer no real benefit. Their scepticism extends to continuous glucose monitoring in people without diabetes, which they warn might provoke needless anxiety without providing clear advantages. The critique culminates in a forceful take down of the personalized-nutrition industry — diet plans based on genetics, which they argue have no solid scientific basis.

Limited legislation

By tracing the origins of the limited control the US Food and Drug Administration (FDA) exerts over food additives and supplements, the authors provide valuable context for why the US food environment is particularly problematic. The Dietary Supplement Health and Education Act of 1994 ensured that dietary supplements do not require premarket approval. The FDA also allows companies to introduce additive chemicals into food if these are merely ‘generally recognized as safe’.

This lax regulatory framework, shaped heavily by food-industry lobbying, stands in stark contrast to the stricter regimes in much of Europe and Latin America. Some countries now warn the public about highly processed foods, yet nutrition-guideline committees in the United States and United Kingdom still decline to mention them as potentially harmful, even as the FDA has been asked to consider the issue in its upcoming review. The status quo persists despite multiple observational studies, Hall’s influential 2019 clinical trial and studies that have replicated his findings.

In terms of solutions, the book argues that “personal responsibility” plays little part in nutrition — a point that, if pushed too rigidly, can feel disempowering. The authors insist that the real challenge lies in reshaping the “toxic food environment” that drives overconsumption. They call for tighter regulation and greater transparency on additives, reformulation of industrial products, and taxes on ultra-processed foods to shift diets towards whole foods, fruit and vegetables.

It’s a powerful message, and one that deserves wider attention, even if the book’s practical diet suggestions are underwhelming: eat less meat, eat more fruit and vegetables, and store junk food out of sight.