IF YOU WANT TO PREVENT ADULT WEIGHT GAIN, walk at least 8,600 steps daily. Are you already overweight and want to dodge obesity? You need to boost your step total by 2,400 steps (for a cumulative 11,000 steps daily). Today we examine the relationship between walking and weight.
Let’s step back to frame the issue. Adults tend to gain weight through middle age. The average weight gain for adults in the United States is 0.5 to one kilogram yearly. While that may not sound like much, such weight gain can lead to obesity over time.
So here’s the good news: The US Centers for Disease Control review suggests that the rate of increase starts to slow in the 30s and 40s and levels in the 50s for many. And then, the average weight drops.
The National Health and Nutritional Examination Survey, involving medical examinations of thousands of individuals each year, appears reliable. The numbers are objective, based on clinician examinations rather than individuals’ self-reporting.
Of course, weight loss can signal conditions such as cancer, depression, gut problems, and other medical problems. Moreover, the projected weight trajectories are population averages. Your weight pathway hinges on your diet, genetics, physical activity, and sleep.
A new study on walking and health
A recently published study analyzed an average of four years of health and activity data from over 6,000 subjects in the US National Institute of Health’s All of Us Research Program.
Study participants wore activity trackers for a minimum of 10 hours daily, allowing study investigators access to their electronic medical records over multiple years. The activity trackers also allowed the researchers to dodge having to make assumptions about activity over time.
Females represented 73 percent of the participants. The subjects had a median age of 57 and a body mass index of 28 (24.3 to 32.9). Seventy-one percent had a college degree, and 84 percent were white.
WALKING AND WEIGHT: 8,200 steps reduces obesity risk
The scientists looked at the association between step count and intensity using commercial activity monitors linked to an individual’s electronic medical health records. Here are the findings:
Individuals walking four miles daily — about 8,200 steps — appeared less likely to become obese or develop sleep apnea, acid reflux, and a major depressive disorder. Moreover, this step volume appeared to be associated with a lower chance of developing high blood pressure (hypertension), diabetes, and sleep apnea.
Overweight participants (with a body mass index of 25 to 29) cut their risk of becoming obese by half (or more) if they increased their step count to 11,000 daily.
The researchers give us this specific example: Individuals with a body mass index (BMI) of 28 could lower their obesity risk by nearly two-thirds (64 percent) by increasing steps from about 6,000 to 11,000 daily.
Step count appeared directly correlated with step intensity, regardless of the bout cadence definition. The relation of step counts with disease risk persisted for diabetes, gastroesophageal reflux disease (GERD), a major depressive episode, and sleep apnea, even when adjusting for step intensity. Step intensity also appeared to be significantly associated with these outcomes.
Here is the take of study author Dr. Evan Brittain, associate professor in the division of cardiovascular medicine at Vanderbilt University Medical Center (USA):
“The relationship with hypertension and diabetes plateaued after about 8,000 to 9,000 steps but the others were linear, meaning higher steps continued to reduce risk,” he said. “I would say that the take home messages are that more steps are better.”
My take: Walking and health
This study reminds us that walking can be a wonderful physical activity and counts as exercise for those who can do it. The study does have some limitations (which the researcher readily volunteer), including the following:
- The researchers could not account for daily step variations between different types of Fitbit models.
- The characteristics of the study participants may limit the generalizability of the findings to more diverse populations. Most subjects were relatively young, female, white, and college-educated. All owned Fitbit devices.
- Participants engaged in more daily steps (median 7,731 steps daily) than the number reported for adults in the USA. I suspect a sedentary individual would benefit even more from upping their step count.
- The data don’t account for non-stepping activities such as swimming or cycling. Furthermore, the consumer devices are not research-grade.
Finally, and perhaps most importantly, the study is observational. We should not infer causality. Reverse causation is possible — a condition leads to taking fewer steps rather than the reverse. The study authors tried to get at the reverse causation problem by focusing only on incident conditions and excluding any incident disease that emerged in the first six months of the monitoring period.
Thank you for joining me in the exploration of walking and weight. Interested in reading more about the power of walking?
