Baseline fitness level may predict future weight-loss success
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Adults with overweight or obesity and very poor baseline physical fitness lost less body weight during an 18-month behavioral weight loss intervention compared with those who had poor or better baseline physical fitness levels, according to findings accepted for presentation at the Endocrine Society Annual Meeting.
“VO2max refers to the maximum amount of oxygen you can utilize during exercise, and is an indicator of cardiorespiratory fitness,” Adnin Zaman, MD, a clinical/research fellow in the division of endocrinology, metabolism and diabetes at the University of Colorado Anschutz Medical Campus in Aurora, told Healio. “An individual with lower cardiorespiratory fitness will not burn as many calories as an individual with higher fitness when exercising at the same relative intensity, and that energetic difference could impact weight loss or weight loss maintenance.”
In a secondary analysis of an interventional trial, Zaman and colleagues analyzed data from 60 inactive adults with overweight or obesity (mean age, 41 years; mean BMI, 34.6 kg/m2; 80% women) enrolled in an 18-month behavioral weight-loss program designed to examine the optimal time to begin exercise within a weight-loss program. The study combined calorie-restricted diet, group-based behavioral support and 6 months of supervised exercise that gradually progressed to 300 minutes per week of moderate-intensity, followed by 12 months of unsupervised exercise. Researchers measured moderate to vigorous physical activity during 1-week periods with a SenseWear armband at baseline, 6, 12 and 18 months. Fitness (VO2max) was measured on a treadmill using indirect calorimetry and categorized based on published age and sex norms. Researchers used a linear mixed-effects model to examine the association between baseline fitness category and changes in body weight, total moderate to vigorous physical activity and moderate to vigorous physical activity in bouts of at least 10 minutes at four time points.
Within the cohort, 33% (n = 20) were classified as having very poor fitness, 45% (n = 27) had poor fitness, 18% (n = 11) had fair fitness and 3% (n = 2) had good fitness. No participants were classified as having excellent or superior fitness levels.
“Due to the low proportion of participants categorized as having fair or better fitness, we created a binary fitness variable (very poor vs. poor or better),” the researchers wrote in an abstract.
Compared with participants who had poor or better baseline fitness, those with very poor fitness had a higher mean BMI (mean, 36.2 kg/m² vs. 33.7 kg/m²; P = .03).
At 6 and 12 months, researchers did not observe between-group differences in weight change; however, at 18 months, adults with very poor fitness lost half the amount of body weight of those with poor or better fitness (mean, 4.3 kg vs. 8.2 kg; P = .07).
At 18 months, participants in both groups increased moderate to vigorous physical activity from their baseline levels; however, levels of moderate to vigorous physical activity accumulated in bouts of at least 10 minutes remained lower among adults with very poor fitness vs. those with poor or better fitness (mean, 24 minutes per day vs. 42 minutes per day; P = .03).
“Total moderate to vigorous physical activity showed a similar pattern,” the researchers wrote in an abstract.
During a virtual presentation Tuesday, Zaman said participants with very poor fitness at baseline may require additional exercise support during a behavioral weight-loss program to achieve the high levels of moderate to vigorous physical activity recommended for weight-loss maintenance.
“What we found is that those with poor or better fitness at baseline are able to achieve significantly higher mean levels of moderate to vigorous physical activity compared with those with very poor fitness,” Zaman said. “This is important because it suggests that baseline fitness may be a moderating factor at 18-month weight loss, as those with very poor fitness lost less weight compared with those with poor or better fitness levels.” – by Regina Schaffer
Reference:
Zaman A, et al. SAT-575. The Endocrine Society Annual Meeting; 2020 (conference canceled/virtual meeting).
Disclosure: Zaman reports no relevant financial disclosures.