Category Archives: Fitness

Waist-hip ratio best for predicting death.

CONFERENCE COVERAGE: EASD 2022: European Association for the Study of Diabetes

Publish date: September 20, 2022

By Mitchel L. Zoler, PhD

Waist-hip ratio beats BMI for predicting obesity’s mortality risk

STOCKHOLM – New evidence continues to show that alternative measures of adiposity than body mass index, such as waist-to-hip ratio, work better for predicting the risk a person with overweight or obesity faces from their excess weight.

A direct comparison of waist-to-hip ratio (WHR), body mass index (BMI), and fat mass index (FMI) in a total of more than 380,000 United Kingdom residents included in the UK Biobank showed that WHR had the strongest and most consistent relationship to all-cause death, compared with the other two measures, indicating that clinicians should pay more attention to adiposity distribution than they do to BMI when prioritizing obesity interventions, Irfan Khan said at the annual meeting of the European Association for the Study of Diabetes.

MDedge News/Mitchel L. Zoler Irfan Khan

Although it’s likely “way too early” to fully replace BMI as a measure of adiposity, because it is so established in guidelines and in practice, it is now time to “use WHR as an adjunct to BMI” suggested Mr. Khan in an interview.

“A lot of work still needs to be done to translate WHR into practice, but I think it’s getting closer,” said Mr. Khan, a medical student at McMaster University, Hamilton, Ont., who performed his analyses in collaboration with a research team based primarily at McMaster.

Moving away from BMI-centric obesity

“This is a timely topic, because guidelines for treating people with obesity have depended so much on BMI. We want to go from a BMI-centric view to a view of obesity that depends more on disease burden,” commented Matthias Blüher, MD, professor of molecular endocrinology and head of the Obesity Outpatient Clinic for Adults at the University of Leipzig (Germany).

MDedge News/Mitchel L. Zoler Dr. Matthias Blüher

For example, the 2016 obesity management guidelines from the American Association of Clinical Endocrinologists and the American College of Endocrinology called for a “complications-centric” approach to assessing and intervening in people with obesity rather than a “BMI-centric” approach.

But Dr. Blüher went a step further in an interview, adding that “waist-to-hip ratio is now outdated,” with adjusted measures of WHR such as waist-to-height ratio “considered a better proxy for all-cause death.” He also gave high marks to the Edmonton Obesity Staging System, which independently added to BMI as well as to a diagnosis of metabolic syndrome for predicting mortality in a sample from the U.S. National Health and Nutrition Examination Survey (NHANES). The Edmonton System also surpassed BMI for disease-severity staging using data from more than 23,000 Canadians with a BMI that denoted obesity.

1 standard deviation increase in WHR linked with a 41% increased mortality

The study reported by Mr. Khan used both epidemiologic and Mendelian randomization analyses on data collected from more than 380,000 U.K. residents included in the UK Biobank database to examine the statistical associations between BMI, FMI, and WHR and all-cause death. This showed that while BMI and FMI both had significant, independent associations with all-cause mortality, with hazard ratios of 1.14 for each 1 standard deviation increase in BMI and of 1.17 for each standard deviation increase in FMI, the link was a stronger 1.41 per standard deviation increase in WHR, he said.

Another analysis that divided the entire UK Biobank study cohort into 20 roughly similar subgroups by their BMI showed that WHR had the most consistent association across the BMI spectrum.

RELATEDWhen do we stop using BMI to diagnose obesity?

Further analyses showed that WHR also strongly and significantly linked with cardiovascular disease death and with other causes of death that were not cardiovascular, cancer-related, or associated with respiratory diseases. And the WHR link to all-cause mortality was strongest in men, and much less robust in women, likely because visceral adiposity is much more common among men, even compared with the postmenopausal women who predominate in the UK Biobank cohort.

One more feature of WHR that makes it an attractive metric is its relative ease of measurement, about as easy as BMI, Mr. Khan said.

The study received no commercial funding, and Mr. Khan had no disclosures.

Dr. Blüher has been a consultant to or speaker on behalf of Amgen, AstraZeneca, Bayer, Boehringer Ingelheim, Lilly, Novartis, Novo Nordisk, and Sanofi.

mzoler@mdedge.com

What’s the Best Time of Day to Exercise? It Depends on Your Goals
Lou Schuler
June 20, 2022

For most of us, the “best” time of day to work out is simple: When we can.

Maybe that’s before or after work. Or when the gym offers free daycare. Or when our favorite instructor teaches our favorite class.

That’s why we call it a “routine.” And if the results are the same, it’s hard to imagine changing it up.

But what if the results aren’t the same?

They may not be, according to a new study from a research team at Skidmore College. The results of a 12-week exercise program were different for morning vs. evening workouts.

Women who worked out in the morning lost more fat, while those who trained in the evening gained more upper-body strength and power. As for men, the performance improvements were similar no matter when they exercised. But those who did so in the evening had a significant drop in blood pressure, among other benefits.

The study is part of a growing body of research showing different results for different times of day among different populations. As it turns out, when you exercise can ultimately have a big effect. And we’re not just talking strength and fat loss, but also heart health, mood, and quality of sleep.

An Accidental Discovery

The original goal of the Skidmore study was to test a unique fitness program with a group of healthy, fit, and extremely active adults in early middle age.

The program includes four workouts a week, each with a different focus: strength, steady-pace endurance, high-intensity intervals, and flexibility (traditional stretching combined with yoga and Pilates exercises).

But because the group was so large – 27 women and 20 men completed the 3-month program – they had to split them into morning and evening workout groups.

It wasn’t until researchers looked at the results that they saw the differences between morning and evening exercise, says lead author Paul Arciero, PhD.

Arciero stresses that participants in every group got leaner and stronger. But the women who worked out in the morning got much bigger reductions in body fat and body-fat percentage than the evening group. Meanwhile, women in the evening group got much bigger gains in upper-body strength, power, and muscular endurance than their morning counterparts.

Among the men, the evening group had significantly larger improvements in blood pressure, cholesterol levels, and the percentage of fat they burned for energy, along with a bigger drop in feelings of fatigue.

Strategic Timing for Powerful Results

Some of these findings are consistent with previous research. For example, a study published in 2021 showed that the ability to exert high effort and express strength and power peaks in the late afternoon, about the same time that your core body temperature is at its highest point.

On the other hand, you’ll probably perform better in the morning when the activity requires a lot of skill and coordination or depends on strategic decision-making.

The findings apply to both men and women.

Performance aside, exercise timing might offer strong health benefits for men with type 2 diabetes, or at high risk for it.

A 2020 study showed that men who exercised between 3 and 6 p.m. saw dramatic improvements in blood sugar management and insulin sensitivity, compared to a group that worked out between 8 and 10 a.m.

They also lost more fat during the 12-week program, even though they were doing the exact same workouts.

Train Consistently, Sleep Well
When you exercise can affect your sleep quality in many ways, says McMaster University neuroscientist Jennifer Heisz, PhD, author of Move the Body, Heal the Mind: Overcome Anxiety, Depression, and Dementia and Improve Focus, Creativity, and Sleep.

First, she says, “exercise helps you fall asleep faster and sleep deeper at night.” (The only exception is if you exercise so intensely or so close to bedtime that your heart rate is still elevated.)

Second, “exercising at a consistent time every day helps regulate the body’s circadian rhythms.” It doesn’t matter if the exercise is in the morning, evening, or anywhere in between. As long as it’s predictable, it will help you fall asleep and wake up at the same times.

Outdoor exercise is even better, she says. The sun is the most powerful regulator of the circadian clock and works in tandem with physical activity.

Third, exercising at specific times can help you overcome jet lag or adjust to an earlier or later shift at work.

“Exercising at 7 a.m.

or between 1 and 4 p.m. helps your circadian clock to ‘fall back’ in time, making it easier to wake up earlier,” Heisz says. If you need to train your body to wake up later in the morning, try working out between 7 and 10 p.m.

All Exercise Is Good, but the Right Timing Can Make It Even Better
“The best time to exercise is when you can fit it in,” Arciero says. “You’ve got to choose the time that fits your lifestyle best.”

But context matters, he notes.

“For someone needing to achieve an improvement in their risk for cardiometabolic disease,” his study shows an advantage to working out later in the day, especially for men.

If you’re more focused on building upper-body strength and power, you’ll probably get better results from training in the afternoon or evening.

And for fat loss, the Skidmore study shows better results for women who did morning workouts.

6

And if you’re still not sure? Try sleeping on it – preferably after your workout.

Sources
Frontiers in Physiology: “Morning Exercise Reduces Abdominal Fat and Blood Pressure in Women; Evening Exercise Increases Muscular Performance in Women and Lowers Blood Pressure in Men.”

Paul Arciero, PhD, professor, Health and Human Physiological Sciences Department, Skidmore College.

BMJ Open Sport & Exercise Medicine: “Diurnal variations in the expression of core-clock genes correlate with resting muscle properties and predict fluctuations in exercise performance across the day.”

Physiological Reports: “Exercise training elicits superior metabolic effects when performed in the afternoon compared to morning in metabolically compromised humans.”

Jennifer Heisz, PhD, associate professor, Department of Kinesiology, McMaster University.