General practitioners often advise their patients to lose weight, but apparently they don’t do it well. According to a University of Oxford study in the journal Family Practice that reanalyzed audio recordings from the U.K. Brief Interventions for Weight Loss trial, advice from GPs is mostly generic and rarely effective. They offer hand-wavy “eat less, do more” platitudes—the equivalent of psychiatrists telling their patients to just be happy. Rarely is it tailored to a person’s existing knowledge, let alone their specific physiology. This seems especially relevant since a second paper this week shows a stunning result: Physiology could be far more important for determining dietary outcomes than willpower. Analyzing dietary habits and molecular data from 609 people before, during, and after they underwent 1-year low-carb or low-fat diets, researchers at Stanford University found there were minimal dietary differences between people who did or did not achieve long-term weight loss. What differed significantly were the proteomic and gut microbiota signatures at baseline. It seems like that’s the sort of precision data we need for more personalized weight loss programs. Cell Reports Medicine

A fascinating study in mice this week suggests the neurochemistry of a “runner’s high,” that oh-yeah-let’s-go phenomenon of reward, pleasure, and the ability to push through the pain could be influenced by the microbiome. Moreover, the microbiome may be profoundly influencing our motivation for exercising in the first place, possibly explaining why performance varies from person to person. Researchers at the University of Pennsylvania uncovered how gut microbes produce metabolites that trigger TRPV1+ sensory neurons. That leads to higher levels of dopamine in the brain and enhanced exercise capability. But without the metabolites, sensory signals are inhibited, exercise-induced dopamine is blunted, and motivation for exercise is reduced. There may be an evolutionary reason for this. Our gut microbiomes may have served as harbingers of nutrient availability throughout the day or year, giving the brain a way to probe for the need to press the body into prolonged physical activity. Wake up… time to dine! Nature

Using anonymized smartphone GPS data from the company Mapbox to study how people use parks and nature preserves in the Greater Toronto Area, researchers from the University of Toronto tracked human activity in 53 green spaces to get a global glimpse of how many people visit these parks and where they go once they’re inside. The data showed that visitors spent most of their time on trails and when off-trail spent the most time scrambling up and down cliff and rock formations. According to the authors, GPS data could mitigate the environmental impact of heavy foot traffic, allowing park managers to adjust trail routes and restrictive fencing based on those activity patterns. PLOS Computational Biology

Tracking human activity in the Hilton Falls and Kelso Conservation Areas outside Toronto as measured by smart phones carried by visitors.

Vitamin A deficiency is the world’s leading preventable cause of childhood blindness, afflicting hundreds of thousands of children a year. It’s also a major cause of maternal mortality and can increase the risk of death from infections like measles and coronavirus. One promising approach to alleviate this form of malnutrition is to fortify foods with vitamin A. But there are lots of challenges in doing so because it readily degrades under the light, moisture, and heat of many normal storage conditions. Now researchers at MIT have developed a potential way to prolong the stability of vitamin A added to food by encapsulating it in a type of FDA-approved polymer sold under the brand names Eudragit or Eudraguard, which is generally regarded as safe. They describe early studies of the vitamin encapsulation technology this week, which they appear to be working to commercialize. PNAS

A graphic depicting the vitamin A encapsulation method. Second Bay Studios

Engineers at Hangzhou Dianzi University and Xi’an Jiaotong University in China and Georgia Institute of Technology in Atlanta have developed a new wearable, low-cost sensor system to collect and analyze data such as breath frequency and rate of exhaled air to diagnose respiratory abnormalities in real time. Their system includes sensors worn under each nostril, a phone app for displaying user data, and a cloud-based data analysis package that uses AI, built into a small, self-powered sensor device that would accelerate diagnoses of sleep apnea, rhinitis, and chronic lung diseases, and allow the user to track COVID-19 rehabilitation. Cell Reports Physical Science (link not functioning at press time)

So instead of a white elephant for Christmas this year, how about a white rhino? Researchers at Osaka University in Japan and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC) in Berlin, Germany, have taken an important step toward possibly saving the mighty beast, which is on the brink. Hunted to near extinction by poachers for their horns, the northern white rhinoceros is already extinct in the wild. Only two females exist in captivity, and no males exist anywhere. Hope exists, however, to use assisted reproductive technology to create northern white rhino embryos in the laboratory and with help of southern white rhinoceros surrogate mothers (a closely related sister species), give birth to a new calf. Toward that end, the researchers took pluripotent stem cells from the northern rhino and derived primordial germ cell-like cells. This is a first step toward making northern white rhino gametes, a process known as in vitro gametogenesis, to derive northern white rhino eggs and sperm in the lab. Science Advances

Editor’s note: This Dispatch was updated to reflect the fact that white rhinos have horns, but they are made of keratin, not ivory.