Age of obesity onset affects subcutaneous adipose tissue cellularity differently in the abdominal and femoral region.

OBJECTIVE: We aimed to examine the effect of age of obesity onset, sex, and their interaction on abdominal and femoral subcutaneous adipose tissue (SAT) morphology (degree of adipocyte hyperplasia or hypertrophy). METHODS: In this cross-sectional study, we isolated adipocytes via collagenase digestion from abdominal and femoral SAT biopsies taken from male and female adults with childhood-onset obesity (CO; n = 8 males, n = 16 females) or adult-onset obesity (AO; n = 8 males, n = 13 females). Regional body composition was measured with dual-energy x-ray absorptiometry and a single-slice abdominal computed tomography scan. Mean adipocyte size was measured in abdominal and femoral SAT and was used to quantify morphology in android and gynoid subcutaneous fat, respectively. RESULTS: Abdominal SAT morphology was more hyperplastic in females with CO than females with AO (p = 0.004) but did not differ between males with CO and males with AO (p = 0.996). Conversely, femoral SAT morphology was more hypertrophic in males and females with CO than those with AO. CONCLUSIONS: Age of obesity onset appears to affect SAT morphology differently in the abdominal and femoral regions of male and female adults. Our findings challenge the notion that SAT is uniformly hyperplastic in CO and hypertrophic in AO.

Improvements in cardiorespiratory fitness, muscle strength and body composition to modest weight loss are similar in those with adult- versus childhood-onset obesity.

Adults who have had obesity from childhood are at greater risk of obesity-related comorbidities compared to those who only develop obesity in adulthood. The main way of mitigating these risks in obesity is with weight loss, which has been shown to positively affect the cardiorespiratory fitness (CRF) and body composition of adults. However, it is unclear whether the response of these outcomes to weight loss may be influenced by age of obesity onset. The objective of our study was to investigate how age of obesity onset mitigates the responsiveness of CRF, muscle strength and body composition to modest weight loss. Measurements were conducted at baseline and 12 weeks. In total, 37 participants (childhood-onset = 19, adult-onset = 18) lost 3.7% ± 0.4% through aerobic exercise and diet. The YMCA cycle ergometer test (YMCA) and the 20-m shuttle run test (20MSR) were used to estimate CRF (mL kg-1 min-1 ) and a handgrip dynamometer was used to estimate muscle strength. Total body composition was assessed by dual-energy x-ray absorptiometry (DEXA). Overall, CRF and body composition improved (time effect: p < 0.05) after 12 weeks. There was no group-by-time interaction for YMCA, 20MSR, muscle strength and body composition variables. Therefore, the present study suggests that individuals with childhood-onset obesity and adult-onset obesity can improve their CRF and body composition similarly after mild weight loss.

The influence of physical activity on neural responses to visual food cues in humans: A systematic review of functional magnetic resonance imaging studies.

This systematic review examined whether neural responses to visual food-cues measured by functional magnetic resonance imaging (fMRI) are influenced by physical activity. Seven databases were searched up to February 2023 for human studies evaluating visual food-cue reactivity using fMRI alongside an assessment of habitual physical activity or structured exercise exposure. Eight studies (1 exercise training, 4 acute crossover, 3 cross-sectional) were included in a qualitative synthesis. Structured acute and chronic exercise appear to lower food-cue reactivity in several brain regions, including the insula, hippocampus, orbitofrontal cortex (OFC), postcentral gyrus and putamen, particularly when viewing high-energy-density food cues. Exercise, at least acutely, may enhance appeal of low-energy-density food-cues. Cross-sectional studies show higher self-reported physical activity is associated with lower reactivity to food-cues particularly of high-energy-density in the insula, OFC, postcentral gyrus and precuneus. This review shows that physical activity may influence brain food-cue reactivity in motivational, emotional, and reward-related processing regions, possibly indicative of a hedonic appetite-suppressing effect. Conclusions should be drawn cautiously given considerable methodological variability exists across limited evidence.

Exploring the acute effects of running on cerebral blood flow and food cue reactivity in healthy young men using functional magnetic resonance imaging.

Acute exercise suppresses appetite and alters food-cue reactivity, but the extent exercise-induced changes in cerebral blood flow (CBF) influences the blood-oxygen-level-dependent (BOLD) signal during appetite-related paradigms is not known. This study examined the impact of acute running on visual food-cue reactivity and explored whether such responses are influenced by CBF variability. In a randomised crossover design, 23 men (mean ± SD: 24 ± 4 years, 22.9 ± 2.1 kg/m2 ) completed fMRI scans before and after 60 min of running (68% ± 3% peak oxygen uptake) or rest (control). Five-minute pseudo-continuous arterial spin labelling fMRI scans were conducted for CBF assessment before and at four consecutive repeat acquisitions after exercise/rest. BOLD-fMRI was acquired during a food-cue reactivity task before and 28 min after exercise/rest. Food-cue reactivity analysis was performed with and without CBF adjustment. Subjective appetite ratings were assessed before, during and after exercise/rest. Exercise CBF was higher in grey matter, the posterior insula and in the region of the amygdala/hippocampus, and lower in the medial orbitofrontal cortex and dorsal striatum than control (main effect trial p ≤ .018). No time-by-trial interactions for CBF were identified (p ≥ .087). Exercise induced moderate-to-large reductions in subjective appetite ratings (Cohen's d = 0.53-0.84; p ≤ .024) and increased food-cue reactivity in the paracingulate gyrus, hippocampus, precuneous cortex, frontal pole and posterior cingulate gyrus. Accounting for CBF variability did not markedly alter detection of exercise-induced BOLD signal changes. Acute running evoked overall changes in CBF that were not time dependent and increased food-cue reactivity in regions implicated in attention, anticipation of reward, and episodic memory independent of CBF.