Quantification of Human Central Adipose Tissue Depots: An Anatomically Matched Comparison Between DXA and MRI

Effects of Hypocaloric Low-Fat, Ketogenic, and Ketogenic and Ketone Supplement Diets on Aldosterone and Renin

CONTEXT

Ketogenic diets (KDs) and low-fat diets (LFD) result in similar weight loss, but have differential cardiometabolic effects on lipids and insulin. Generally, weight loss decreases renin-angiotensin-aldosterone system (RAAS) activity.

OBJECTIVE

Investigate the effects of KDs with varying sodium content vs LFD on RAAS in overweight and obese adults.

METHODS

Twenty-eight participants were randomized 1:1 to a KD + ketone salt supplement (KD + KS) or a KD + placebo (KD + PL) arm with prepared hypocaloric meals. Twelve participants were enrolled in a post hoc LFD arm. Serum renin, aldosterone, and anthropometric and metabolic biomarkers were assessed at 0, 2, 4, and 6 weeks. Linear mixed models with random intercepts were used to compare between group differences controlling for sex and body mass index.

RESULTS

Participants had a median age of 33 years, 51% female, weighed 91.3 kg, with body mass index 30.6 kg/m2. At 6 weeks, weight decreased by 6, 8, and 7 kg on average in the KD + KS, KD + PL, and LFD groups, respectively (P < .05). Aldosterone increased by 88% and 144% in the KD + PL and KD + KS groups, respectively, but did not change in the LFD after 6 weeks while renin decreased across groups. Systolic and diastolic blood pressure did not change in the KD + PL and KD + KS groups. Log ketones were positively associated with aldosterone (P < .001). Aldosterone was not associated with cardiovascular measures including blood pressure and ejection fraction (P > .05).

CONCLUSION

KD reduced weight and increased aldosterone without worsening cardiometabolic risk factors. Future KD studies are needed to elucidate mechanistic connections between ketones and aldosterone.

Body weight and fat trajectories of Black and White women in the first postpartum year

OBJECTIVE

The aim of this study was to examine changes in body weight and fat in Black and White women during the first postpartum year and to determine whether there is preferential retention of fat mass and abdominal fat.

METHODS

Body composition was quantified by dual-energy x-ray absorptiometry in Black (n = 49) and White (n = 85) women at 6 to 8 weeks, 6 months, and 12 months after delivery of a singleton infant.

RESULTS

Weight, fat mass, percent body fat, and fat in the trunk, android, gynoid, and limb regions decreased from 6 to 8 weeks to 12 months in White women, but not in Black women (fat mass, adjusted mean [SE]: 29.6 [1.3] to 26.9 [1.3] kg in White women and 34.5 [1.5] to 36.8 [1.8] kg in Black women). In the entire sample, fat mass was higher at 6 months than at 6 to 8 weeks, independent of weight change; visceral fat was higher at 12 months (686 [45] g) than at 6 to 8 weeks (611 [42] g) and 6 months (626 [43] g); and android fat was higher at 12 months than at 6 months, independent of fat change.

CONCLUSIONS

Black women were less likely than White women to lose weight and fat in the postpartum period. There was preferential retention of fat in the abdominal area.

Comparison between DXA and MRI for the Visceral Fat Assessment in Athletes

The use of dual-energy X-ray absorptiometry (DXA) may be invalid for assessing athletes with larger bodies, larger lean body mass, and thicker trunks. This study compared the athletes' visceral adipose tissue (VAT) assessed using DXA and magnetic resonance imaging (MRI). Eighty-two Japanese male collegiate athletes from 18 sports participated in this study. VAT was assessed using the dual-energy scan that coincided with the 4th lumbar vertebra. The sum of eight magnetic resonance slices corresponding to the region of the dual-energy scan was used for comparison. The VAT volume was higher with the dual-energy scan than with MRI (difference: 35 cm³, p<0.01). A significant correlation was noted between the volumes measured using both modalities (r=0.88, p<0.01). Magnetic resonance-derived volumes less than 600 cm³ showed a stronger significant correlation with dual-energy-derived volumes. However, magnetic resonance-derived VAT volumes exceeding 600 cm³ were not significantly correlated with dual-energy-derived volumes. In conclusion, VAT volumes derived from DXA were larger and significantly correlated with those derived from MRI across a wide range of values. Methods using DXA for assessing the visceral fat volume may require adjustment to estimate abdominal visceral fat volume in athletes, with care taken when using such methods for heavyweight athletes.

Effectiveness of a lifestyle weight-loss intervention targeting inactive former elite athletes: the Champ4Life randomised controlled trial

OBJECTIVES

Many athletes struggle in managing the end of their career, often gaining weight and adopting unhealthy lifestyles. Lifestyle programmes targeting former athletes who have gained substantial fat mass (FM) postsports career are lacking. We studied the effects of the Champ4Life programme on body composition and other health-related outcomes in former elite athletes with overweight or obesity.

METHODS

Ninety-four former athletes(42.4±7.3 y, 34.0% female) were recruited and randomly assigned to either an intervention group (IG; n=49) or a control group (CG; n=45). The IG attended 12 educational sessions addressing physical activity, weight management and nutrition. They also had a nutrition appointment aimed to prescribe a moderate caloric deficit(~300-500 kcal/day). Dual-energy X-ray absorptiometry was used to assess body composition. The Short-Form Health Survey-36 questionnaire was used to measure general health-related quality of life. Blood samples were collected to assess cardiometabolic health parameters.

RESULTS

At 12 months, the IG lost more weight (estimated difference (ED)=-5.3 kg; -6.9 to -3.8), total FM (ED=-4.1 kg; -5.4 to -2.8) and abdominal FM (ED=-0.49 kg; -0.64 to -0.33) than did the CG (p's<0.001). Cardiometabolic health markers also improved significantly (p<0.05) more in the IG at 12 months (insulin (ED=-4.9 μU/mL;-8.0 to -1.8); homoeostatic model assessment (ED=-1.2; -2.1 to -0.4); total cholesterol (ED=-21.8 mg/dL; -35.4 to -8.2); low-density lipoprotein (ED=18.2 mg/dL;-29.2 to -7.1)), as did quality-of-life dimensions (physical functioning (ED=11.7; 6.5 to 16.9); physical role (ED=17.6; 2.1 to 33.0); general health (ED=19.4; 11.4 to 27.4); vitality (ED=13.3; 5.3 to 21.3) and mental health (ED=12.3; 4.1 to 20.6)).

CONCLUSIONS

The Champ4Life programme was effective in substantially reducing total and abdominal FM while preserving fat-free mass and improving health-related markers. These findings will enable evidence-based decisions when implementing lifestyle interventions targeting retired elite athletes.

TRIAL REGISTERATION NUMBER

NCT03031951.

The Effects of a 6-Week Controlled, Hypocaloric Ketogenic Diet, With and Without Exogenous Ketone Salts, on Body Composition Responses

Background: Ketogenic diets (KDs) that elevate beta-hydroxybutyrate (BHB) promote weight and fat loss. Exogenous ketones, such as ketone salts (KS), also elevate BHB concentrations with the potential to protect against muscle loss during caloric restriction. Whether augmenting ketosis with KS impacts body composition responses to a well-formulated KD remains unknown. Purpose: To explore the effects of energy-matched, hypocaloric KD feeding (<50 g carbohydrates/day; 1.5 g/kg/day protein), with and without the inclusion of KS, on weight loss and body composition responses. Methods: Overweight and obese adults were provided a precisely defined hypocaloric KD (~75% of energy expenditure) for 6 weeks. In a double-blind manner, subjects were randomly assigned to receive ~24 g/day of a racemic BHB-salt (KD + KS; n = 12) or placebo (KD + PL; n = 13). A matched comparison group (n = 12) was separately assigned to an isoenergetic/isonitrogenous low-fat diet (LFD). Body composition parameters were assessed by dual x-ray absorptiometry and magnetic resonance imaging. Results: The KD induced nutritional ketosis (>1.0 mM capillary BHB) throughout the study (p < 0.001), with higher fasting concentrations observed in KD + KS than KD + PL for the first 2 weeks (p < 0.05). There were decreases in body mass, whole body fat and lean mass, mid-thigh muscle cross-sectional area, and both visceral and subcutaneous adipose tissues (p < 0.001), but no group differences between the two KDs or with the LFD. Urine nitrogen excretion was significantly higher in KD + PL than LFD (p < 0.01) and trended higher in KD + PL compared to KD + KS (p = 0.076), whereas the nitrogen excretion during KD + KS was similar to LFD (p > 0.05). Conclusion: Energy-matched hypocaloric ketogenic diets favorably affected body composition but were not further impacted by administration of an exogenous BHB-salt that augmented ketosis. The trend for less nitrogen loss with the BHB-salt, if manifested over a longer period of time, may contribute to preserved lean mass.

Comparison of Ketogenic Diets with and without Ketone Salts versus a Low-Fat Diet: Liver Fat Responses in Overweight Adults

Ketogenic diets (KDs) often contain high levels of saturated fat, which may increase liver fat, but the lower carbohydrate intake may have the opposite effect. Using a controlled feeding design, we compared liver fat responses to a hypocaloric KD with a placebo (PL) versus an energy-matched low-fat diet (LFD) in overweight adults. We also examined the added effect of a ketone supplement (KS). Overweight adults were randomized to a 6-week KD (KD + PL) or a KD with KS (KD + KS); an LFD group was recruited separately. All diets were estimated to provide 75% of energy expenditure. Weight loss was similar between groups (p > 0.05). Liver fat assessed by magnetic resonance imaging decreased after 6 week (p = 0.004) with no group differences (p > 0.05). A subset with nonalcoholic fatty liver disease (NAFLD) (liver fat > 5%, n = 12) showed a greater reduction in liver fat, but no group differences. In KD participants with NAFLD, 92% of the variability in change in liver fat was explained by baseline liver fat (p < 0.001). A short-term hypocaloric KD high in saturated fat does not adversely impact liver health and is not impacted by exogenous ketones. Hypocaloric low-fat and KDs can both be used in the short-term to significantly reduce liver fat in individuals with NAFLD.

The Appropriateness Criteria of Abdominal Fat Measurement at the Level of the L1-L2 Intervertebral Disc in Patients With Obesity

BACKGROUND

In this study, we proposed to use MR images at L1-L2 (lumbar) intervertebral disc level to measure abdominal fat area in patients with obesity. The quantitative results would provide evidence for the individualized assessment of the severity of obesity.

METHODS

All patients in the IRB-approved database of Beijing Friendship Hospital who underwent bariatric surgery between November 2017 and November 2019 were recruited. We retrospectively reviewed upper abdominal magnetic resonance (MR) data before surgery. We analyzed the correlation and consistency of the area of abdominal subcutaneous adipose tissue (ASAT) and visceral adipose tissue (VAT) measured at the L1-L2 and L2-L3 levels on MR images. We randomly distributed the cases into prediction model training data and testing data at a ratio of 7:3.

RESULTS

Two hundred and forty-five subjects were included. The ASAT and VAT results within the L1-L2 and L2-L3 levels were very similar and highly correlated (male^ASAT: r=0.98, female^ASAT: r=0.93; male^VAT: r=0.91, female^VAT: r=0.88). There was no substantial systematic deviation among the results at the two levels, except for the ASAT results in males. The intraclass correlation coefficients (ICCs) were 0.91 and 0.93 for male^ASAT and female^ASAT, and 0.88 and 0.87 for male^VAT and female^VAT, respectively. The ASAT/VAT area at the L2-L3 level was well predicted. The coefficient β of linear regression that predicted L2-L3 ASAT from L1-L2 ASAT was 1.11 for males and 0.99 for females. The R-squares were 0.97 and 0.91, respectively. For VAT prediction, the coefficient β was 1.02 for males and 0.96 for females. The R-squares were 0.82 and 0.77, respectively.

CONCLUSION

For patients with obesity, the L1-L2 intervertebral disc level can be used as the substitution of L2-L3 level in abdominal fat measurement.

Effect of high intensity interval training on body composition in women before and after menopause: a meta-analysis

NEW FINDINGS

What is the topic of this review? A meta-analysis of the efficacy of high intensity interval training (HIIT) in reducing weight, total fat mass (FM) and (intra)-abdominal FM in normal-weight and overweight/obese women before and after menopause. What advances does it highlight? HIIT programmes in women significantly decrease body weight and total and abdominal FM. Their effects are more evident in pre- than in postmenopausal women. Cycling HIIT seems more effective than running, especially in postmenopausal women, and training interventions longer than 8 weeks comprising three sessions a week should be promoted.

ABSTRACT

High-intensity interval training (HIIT) is a stimulating modality for reducing body weight and adipose tissue. The purpose of this meta-analysis was to assess the efficacy of HIIT in reducing weight, total fat mass (FM) and (intra)-abdominal FM in normal-weight and overweight/obese women before and after menopause. A structured electronic search was performed to find all publications relevant to our review. Stratified analyses were made of hormonal status (pre- vs. postmenopausal state), weight, HIIT modalities (cycling vs. running), programme duration (< or ≥8 weeks) and the methods used to measure body composition (dual-energy X-ray absorptiometry vs. computed tomography, Magnetic Resonance Imaging and others). A total of 38 studies involving 959 subjects were included. Our meta-analysis showed that overall HIIT programmes significantly decrease weight, total and abdominal FM in women. Both normal weight and overweight/obese women lost total FM after HIIT protocols whereas HIIT was only effective in decreasing abdominal FM in women with excess adiposity. When pre- and postmenopausal women were considered separately, the effect of HIIT on weight, total and abdominal FM were only significant before menopause. Cycling HIIT seemed more effective than running, especially in postmenopausal women, and training interventions longer than 8 weeks comprising three sessions were more efficient. HIIT is a successful strategy to lose weight and FM in normal weight and overweight/obese women. However, further studies are still needed to draw meaningful conclusions about the real effectiveness of HIIT protocols in postmenopausal women.