Hunger Games

In this week's Rundown, a hard workout may dull your appetite, sitting too long is once again a bad idea and paying attention to fitness young improves cognition later.

The Rundown

Hunger Games. If your goal is to be less hungry after your workout, you might consider picking up the pace. A new study (read the abstract) published in Nature investigated what makes us feel hungry or not, after a workout and found that a single molecule produced post-exercise dulls hunger. The molecule, which was found in mice, humans and racehorses showed up in greater numbers after strenuous exercise.

The study began with mice who were put on treadmills to run until they were worn out. The researchers drew blood before and after and found one molecule, a combination of lactate and amino acid, had increased more than any other. They named it lac-phe and gave a version of it to obese mice whose food intake subsequently dropped more than 30 percent.

The scientists then bred mice that produced little to no lac-phe and made them run on treadmills five times a week for several weeks. They ate a lot of kibble and gained around 25 percent more weight than the control group. Next, the team looked for lac-phe in other exercising animals and found that in racehorses, the molecule existed in their bloodstream in much higher levels after a hard run than it did before.

To study the process in humans, the researchers had eight healthy young men workout three times. They cycled at an easy pace for 90 minutes, lifted weights and did several 30-second sprints on a stationary bike. The levels of lac-phe increased after each type of exercise but were highest after the sprints. The casual workout produced the least amount of the molecule in their blood.

If lac-phe works the same in humans as it does in mice, increasing the intensity of a workout may make us less hungry afterward. The study however, does not reveal how lac-phe might interact with our brain cells to affect our appetite, how intense an exercise needs to be or how long the molecule’s effects might last. Since the human participants were young men, it also doesn’t show if lac-phe works in the same ways in women or in older populations.

Lift Off. An international study involving over 100,000 people in 21 countries has provided new evidence to the argument that prolonged sitting may be bad for your health. Researchers followed individuals for an average of 11 years and found that those who sat for six to eight hours a day increased their risk for early death and heart disease by 12-13 percent.

For those who sat more than eight hours a day, the news was particularly bad, as their risk rose by 20 percent. Results were a little better for people who sat the most but were also the most active. Their risk increased by about 17 percent.

Health sciences professor Scott Lear, a co-author of the study, noted that for people sitting more than four hours a day, replacing a half hour with exercise reduced their risk of early death and heart disease by two percent.

Lear added that the combination of sitting and inactivity that the study looked at accounted for 8.8 percent of all deaths, “which is close to the contribution of smoking” (10.6 percent in Lear’s study). The solution to this global problem, he says, is a simple one and “scheduling time to get out of that chair is a great start.”

Dementia Protection Starts Early. The first significant study (read the abstract) to explore links between objectively measured fitness and obesity in childhood with cognition in middle age has found that better performance on physical tests is related to better cognition later in life and may protect against dementia.

Researchers followed more than 1200 people from 1985, when they were between 7 and 15 years old until 2017-2019. In 1985 the participants were assessed for cardiorespiratory fitness, muscular power and endurance and waist-to-hip ratio. Between 2017-2019, the group (then aged 39-50) took a series of computerized tests to assess their cognitive function.

The results showed that children with the highest levels of cardio-respiratory and muscular fitness and lower average waist-to-hip ratio had higher midlife scores in tests that determined processing speed and attention and cognitive function.

Co-lead of the study, Associate Professor Michele Callisaya, notes that protective strategies against future decline may need to start in early childhood “so that the brain can develop sufficient reserve against developing conditions such as dementia in older life.”

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This week’s vintage moment in fitness culture is brought to you by pilates and the glamorous Joan Collins, 1976. Photo credit: Eddie Sanderson/Getty Images.