A new US study is set to examine whether wearing a weighted vest at least 6 hours a day preserves bone health in older obese adults on a weight-loss diet.
Researchers will randomize 192 obese 60- to 85-year-olds to diet alone, diet plus a weighted vest, or diet plus resistance exercise for a year in the Incorporating Nutrition, Vests, Education, and Strength Training in Bone Health (INVEST) clinical trial.
INVEST — which follows a promising shorter smaller pilot study and is being supported by a $2.9 million grant from the US National Institute on Aging — will start enrolling patients in 2 months, with anticipated completion in April 2024.
"We are recruiting folks who would be recommended to lose weight based on current guidelines," principal investigator Kristen M. Beavers, PhD, MPH, RD, Department of Health and Exercise Science at Wake Forest University, Winston-Salem, North Carolina, told Medscape Medical News in an email.
The study is designed to lead to 10% weight loss, she said, which typically is associated with a 2% loss of bone mass.
In turn, "limited randomized controlled trial data suggest that this degree of weight and bone loss is associated with increased risk of frailty fractures (ie, hip, pelvis, upper arm, or shoulder fractures)," which can be debilitating for older adults, she said.
Their group previously showed that seniors who lifted weights while restricting calories lost less muscle and had stronger bones.
"I would love it if people would do regular resistance training, but they just don't," Beavers noted in a press release from the university.
Instead, wearing a vest with pockets that can hold 2-ounce weights to replace each equivalent loss of body weight, up to 10 pounds, "is a more passive but potentially as effective alternative" to resistance exercise to reduce frailty fracture risk, she suggested.
Promising Pilot Study in Which Vest Was Worn for 6 Hours a Day
In addition to being unable to afford a gym membership or finding it difficult to get to a gym, "many older adults simply cannot perform the volume or intensity of activity which is necessary to preserve bone during weight loss," explains Beavers.
In a randomized pilot study, published in the Journal of Osteoporosis and Physical Activity in 2017, Jessica L. Kelleher, MSc, of Wake Forest University, who is now a research coordinator at the Atlanta VA Medical Center, Georgia, investigated the effect on bone health from use of a weighted vest in older obese adults as part of her master's thesis.
Twenty obese adults received a 1100 to 1300 calorie/day diet intervention (Medifast meal replacements, conventional food, and nutrition counseling) for 22 weeks.
Seventeen similar patients received the diet intervention and were also asked to wear a weighted vest (Hyper Vest PRO, Hyperwear) every day, building up to 10 hours a day.
Participants were a mean age of 70 years, were mainly women (79%), and were a mean weight of 97 kg (213 pounds).
In each group, roughly 89% of participants completed the study and they lost an average of about 11 kg (24 pounds).
"Several of our pilot [study] participants commented that it was just easier for them to get out of bed in the morning, put on the vest for a few hours, and then take it off mid-day," Beavers said, so they wore it for an "amazing" average of 6.7 hours a day for 6 months.
The vest wearers benefited from better bone health, although this was not significant, possibly because of the small sample size.
Specifically, the average loss of total hip bone mineral density (BMD, measured by dual-energy X-ray absorptiometry [DXA]) was less in the diet-plus-vest group than the diet-only group (–0.6% vs –1.9%; P = .08).
And the average serum levels of bone-specific alkaline phosphatase (BALP) increased by 3.8% in the diet-plus-vest group but decreased by 4.6% in the diet-only group (P = .07).
INVEST, a Larger, Longer Study, Will Have Three Groups
Like the pilot study, INVEST is enrolling older adults with a body mass index of 30 to 40 kg/m2, but the study will also include a resistance exercise group.
All participants will receive a calorie-restricted diet plan and registered-dietitian-led group counseling sessions (weekly for 6 months, then bimonthly for 6 months).
Once a participant meets their 10% weight-loss goal, they will then switch to a maintenance strategy with fewer meal replacements and more regular food, Beavers said, which is expected to occur at around 6 months after the trial starts.
The primary study outcome is total hip trabecular volumetric BMD and secondary outcomes include measures of other factors related to fracture risk.
"I am hopeful that we'll see participants lose weight and that the vest use is able to reduce weight-loss-associated bone loss to a similar degree as resistance training (a strategy which is somewhat effective but has barriers to large-scale implementation)," Beavers said.
"My suspicion is that bone loss during active weight loss is the most detrimental," she added, "and if this is the case, then one might speculate that you only need to wear the vest during the active weight-loss phase, which for most folks is 3-6 months."
The study vest sells for about $200 and participants in the vest group will be instructed to wear one for up to 8 hours/day (hoping they will wear it 6 hours/day), for 12 months in this study.
The resistance training consists of structured exercise training 3 days/week.
INVEST is funded by a grant from the National Institute on Aging. The pilot study was supported by the Arthritis and Musculoskeletal Disease Research Center, Translational Science Center, and Center for Integrated Medicine at the Wake Forest School of Medicine. An in-kind product donation was made by Jason Pharmaceuticals, a wholly owned subsidiary of Medifast. The researchers have no direct financial interest in the sponsors or the product being studied.
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Cite this: Can a Weighted Vest Preserve Bone as Seniors Lose Weight? - Medscape - Feb 07, 2020.