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Systematic review of the prospective association of daily step counts with risk of mortality, cardiovascular disease, and dysglycemia.
Hall, KS, Hyde, ET, Bassett, DR, Carlson, SA, Carnethon, MR, Ekelund, U, Evenson, KR, Galuska, DA, Kraus, WE, Lee, IM, et al
The international journal of behavioral nutrition and physical activity. 2020;17(1):78
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The health benefits of physical activity for people of all ages, fitness levels, and sociodemographic backgrounds are well-documented. The main aim of this study was to provide an updated description of the association between daily step counts and subsequent cardiovascular disease (CVD) morbidity or mortality, dysglycaemia, and all-cause mortality in adults and the patterns of these associations. This study is a systemic review of 17 studies from 13 different cohorts. Participants’ mean age ranged from 49.7 to 78.9 years with samples comprised of 46.9% female participants on average. Results showed that increasing steps per day is beneficial for health: taking more steps per day was associated with lower risk of all-cause mortality, and lower risk of CVD morbidity or mortality. These associations appear to hold across age, gender, and weight status. Authors conclude that this additional evidence will help guide meaningful volume targets that can be used for health care, education, and behavioural interventions, and potentially inform the development of public health guidelines for steps and health.
Abstract
BACKGROUND Daily step counts is an intuitive metric that has demonstrated success in motivating physical activity in adults and may hold potential for future public health physical activity recommendations. This review seeks to clarify the pattern of the associations between daily steps and subsequent all-cause mortality, cardiovascular disease (CVD) morbidity and mortality, and dysglycemia, as well as the number of daily steps needed for health outcomes. METHODS A systematic review was conducted to identify prospective studies assessing daily step count measured by pedometer or accelerometer and their associations with all-cause mortality, CVD morbidity or mortality, and dysglycemia (dysglycemia or diabetes incidence, insulin sensitivity, fasting glucose, HbA1c). The search was performed across the Medline, Embase, CINAHL, and the Cochrane Library databases from inception to August 1, 2019. Eligibility criteria included longitudinal design with health outcomes assessed at baseline and subsequent timepoints; defining steps per day as the exposure; reporting all-cause mortality, CVD morbidity or mortality, and/or dysglycemia outcomes; adults ≥18 years old; and non-patient populations. RESULTS Seventeen prospective studies involving over 30,000 adults were identified. Five studies reported on all-cause mortality (follow-up time 4-10 years), four on cardiovascular risk or events (6 months to 6 years), and eight on dysglycemia outcomes (3 months to 5 years). For each 1000 daily step count increase at baseline, risk reductions in all-cause mortality (6-36%) and CVD (5-21%) at follow-up were estimated across a subsample of included studies. There was no evidence of significant interaction by age, sex, health conditions or behaviors (e.g., alcohol use, smoking status, diet) among studies that tested for interactions. Studies examining dysglycemia outcomes report inconsistent findings, partially due to heterogeneity across studies of glycemia-related biomarker outcomes, analytic approaches, and sample characteristics. CONCLUSIONS Evidence from longitudinal data consistently demonstrated that walking an additional 1000 steps per day can help lower the risk of all-cause mortality, and CVD morbidity and mortality in adults, and that health benefits are present below 10,000 steps per day. However, the shape of the dose-response relation is not yet clear. Data are currently lacking to identify a specific minimum threshold of daily step counts needed to obtain overall health benefit.
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Body-composition changes in the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE)-2 study: a 2-y randomized controlled trial of calorie restriction in nonobese humans.
Das, SK, Roberts, SB, Bhapkar, MV, Villareal, DT, Fontana, L, Martin, CK, Racette, SB, Fuss, PJ, Kraus, WE, Wong, WW, et al
The American journal of clinical nutrition. 2017;105(4):913-927
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Aging is associated with a decline in both the quantity and quality of fat-free mass (FFM) in parallel with increases in body weight and adiposity. Calorie restriction (CR) is the only dietary intervention that has shown promise regarding a reduction in the rate of biological aging in many nonhuman species. The aim of this study was to examine differential effects of CR on men and women and in normal-weight compared with overweight individuals. CALERIE-2 was a 2-year, multicentre, parallel-group, randomised controlled trial. The participants were randomly assigned to one of the two groups; CR group or the ad libitum control. Results show that at the end of the 2-year CR period, - body composition was relatively higher in FFM and lower in fat mass (FM) [72% FFM, 28% FM] compared with baseline [67% FFM, 33% FM]. - large improvements were observed in indexes of central adiposity, including smaller waist circumference and reductions in percentage of trunk fat in this nonobese population. Authors conclude that body composition is not adversely affected by CR in the absence of prescribed exercise. In fact, maintaining a sustained level of physical activity during CR may be required to help preserve body-composition profiles commensurate with healthy aging.
Abstract
Background: Calorie restriction (CR) retards aging and increases longevity in many animal models. However, it is unclear whether CR can be implemented in humans without adverse effects on body composition.Objective: We evaluated the effect of a 2-y CR regimen on body composition including the influence of sex and body mass index (BMI; in kg/m2) among participants enrolled in CALERIE-2 (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy), a multicenter, randomized controlled trial.Design: Participants were 218 nonobese (BMI: 21.9-28.0) adults aged 21-51 y who were randomly assigned to 25% CR (CR, n = 143) or ad libitum control (AL, n = 75) in a 2:1 ratio. Measures at baseline and 12 and 24 mo included body weight, waist circumference, fat mass (FM), fat-free mass (FFM), and appendicular mass by dual-energy X-ray absorptiometry; activity-related energy expenditure (AREE) by doubly labeled water; and dietary protein intake by self-report. Values are expressed as means ± SDs.Results: The CR group achieved 11.9% ± 0.7% CR over 2-y and had significant decreases in weight (-7.6 ± 0.3 compared with 0.4 ± 0.5 kg), waist circumference (-6.2 ± 0.4 compared with 0.9 ± 0.5 cm), FM (-5.4 ± 0.3 compared with 0.5 ± 0.4 kg), and FFM (-2.0 ± 0.2 compared with -0.0 ± 0.2 kg) at 24 mo relative to the AL group (all between-group P < 0.001). Moreover, FFM as a percentage of body weight at 24 mo was higher, and percentage of FM was lower in the CR group than in the AL. AREE, but not protein intake, predicted preservation of FFM during CR (P < 0.01). Men in the CR group lost significantly more trunk fat (P = 0.03) and FFM expressed as a percentage of weight loss (P < 0.001) than women in the CR group.Conclusions: Two years of CR had broadly favorable effects on both whole-body and regional adiposity that could facilitate health span in humans. The decrements in FFM were commensurate with the reduced body mass; although men in the CR group lost more FFM than the women did, the percentage of FFM in the men in the CR group was higher than at baseline. CALERIE was registered at clinicaltrials.gov as NCT00427193.
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Enhanced cortisol production rates, free cortisol, and 11beta-HSD-1 expression correlate with visceral fat and insulin resistance in men: effect of weight loss.
Purnell, JQ, Kahn, SE, Samuels, MH, Brandon, D, Loriaux, DL, Brunzell, JD
American journal of physiology. Endocrinology and metabolism. 2009;296(2):E351-7
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Excess abdominal fat in men is a risk factor for both type 2 diabetes and cardiovascular disease. The aim of this study was to test the hypothesis that increased cortisol levels contribute to increased abdominal fat and insulin resistance in men. Twenty-four healthy men aged 18-70 took part in the study. Eight of the participants, who were obese, were put on a calorie-controlled weight loss diet. Cortisol production rate (CPR) and free cortisol (FC) were correlated with increased intra-abdominal fat (IAF) and decreased insulin sensitivity (Si). Cortisol levels were not correlated with subcutaneous fat (SQF). CPR and FC did not change with weight loss, suggesting that cortisol levels could influence the distribution of body fat upon weight regain. The authors concluded that their findings support a role for activation of the HPA axis and abnormal cortisol secretion in determining body fat distribution and predisposing these men to type 2 diabetes.
Abstract
Controversy exists as to whether endogenous cortisol production is associated with visceral obesity and insulin resistance in humans. We therefore quantified cortisol production and clearance rates, abdominal fat depots, insulin sensitivity, and adipocyte gene expression in a cohort of 24 men. To test whether the relationships found are a consequence rather than a cause of obesity, eight men from this larger group were studied before and after weight loss. Daily cortisol production rates (CPR), free cortisol levels (FC), and metabolic clearance rates (MCR) were measured by stable isotope methodology and 24-h sampling; intra-abdominal fat (IAF) and subcutaneous fat (SQF) by computed tomography; insulin sensitivity (S(I)) by frequently sampled intravenous glucose tolerance test; and adipocyte 11beta-hydroxysteroid dehydrogenase-1 (11beta-HSD-1) gene expression by quantitative RT-PCR from subcutaneous biopsies. Increased CPR and FC correlated with increased IAF, but not SQF, and with decreased S(I). Increased 11beta-HSD-1 gene expression correlated with both IAF and SQF and with decreased S(I). With weight loss, CPR, FC, and MCR did not change compared with baseline; however, with greater loss in body fat than lean mass during weight loss, both CPR and FC increased proportionally to final fat mass and IAF and 11beta-HSD-1 decreased compared with baseline. These data support a model in which increased hypothalamic-pituitary-adrenal activity in men promotes selective visceral fat accumulation and insulin resistance and may promote weight regain after diet-induced weight loss, whereas 11beta-HSD-1 gene expression in SQF is a consequence rather than cause of adiposity.