• Posted September 17, 2021

What Helps Your Heart More, Losing Fat or Gaining Muscle?

Shedding excess weight does much more for the long-term heart health of young people than building muscle, new research suggests.

It's not that gaining muscle while young proved to be a cardiovascular problem. It's just that losing fat offered bigger heart benefits.

"We absolutely still encourage exercise," said study lead author Joshua Bell, a senior research associate in epidemiology at the University of Bristol in England.

"There are many other health benefits, and strength is a prize in itself," he said. "We may just need to temper expectations for what gaining muscle can really do for avoiding heart disease. Fat gain is the real driver."

The study followed more than 3,200 Brits born in the 1990s. It found those who had primarily lost fat during adolescence and young adulthood were much less likely than those who had gained muscle to develop risk factors such as high glucose, inflammation or "bad" cholesterol by age 25.

Participants had scans to assess levels of body fat and lean mass at ages 10, 13, 18 and 25. Handgrip strength tests were also assessed at 12 and 25.

At 25, participants underwent blood pressure and blood sample testing to assess levels of roughly 200 metabolic factors viewed as "a gateway for heart disease and other health problems," Bell explained.

Such factors included insulin, C-reactive protein, cholesterol, triglycerides, glucose, creatinine and branched chain amino acids.

The result: For lowering risk factors for heart disease, "changes in body fat seem to matter much more than changes in muscle," Bell said. By some measures -- such as lowering levels of "bad" cholesterol -- fat loss appeared to be as much as five times more protective than muscle gain, he added.

"Muscle gain only seemed beneficial when it happened in adolescence, between 13 and 18 years old," Bell said. "This is a busy time of growth and maturity, and might be when we should promote some muscle gain as well. [Heart] benefits seem to fade after then."

His bottom-line message: While muscle is important for outcomes like mobility and independence, fat control seems to be a higher priority when it comes to keeping markers for heart disease in check.

The results were published recently in PLOS Medicine.

Bell stressed that the findings are critical because the seeds of future heart trouble are sown among youths and adolescents, who are otherwise healthy.

While "serious events like heart attacks don't tend to happen until older ages, heart disease doesn't happen overnight," Bell noted.

Lona Sandon is an associate professor in the school of health professions at UT Southwestern Medical Center in Dallas, and reviewed the study findings.

She said you should aim to prevent excess fat gain from the start, rather than focus on fat loss later.

"Instill healthy eating and activity habits early on to maintain a healthy body weight throughout childhood and adolescence for the best chance of reducing early onset of heart disease risk factors," said Sandon. "And by early on, I mean in the womb and infancy."

There should be focus on educating parents about healthy pregnancies and healthy feeding patterns, Sandon advised. "Start with breastfeeding and feeding healthy whole foods and age-appropriate portions during infancy and early childhood," she said.

Restricting calories during childhood is generally not a good idea, as this is a time of growth, Sandon cautioned. "Calories and quality foods are needed for proper growth and development," she said.

Instead, exercise and sports can be a great way to keep a growing body trim. "Active play goes a long way toward keeping kids fit without putting the focus on body fat," Sandon stressed. "Also active kids may be more likely to carry over those active habits into adulthood."

More information

Stanford Children's Health has more on the link between childhood health and heart disease risk.

SOURCES: Joshua A. Bell, PhD, senior research associate, epidemiology, MRC Integrative Epidemiology Unit, University of Bristol, United Kingdom; Lona Sandon, PhD, RDN, LD, program director and associate professor, department of clinical nutrition, school of health professions, UT Southwestern Medical Center, Dallas; PLOS Medicine, Sept. 9, 2021