Areas of fat loss in overweight young females following an 8-week period of energy intake reduction

Hypoxia promotes white adipose tissues browning in rats under simulated environment at altitude of 5000 m

People living in plains tend to decrease in body weight or body fat percentage after entering the plateau. Previous studies have found that plateau animals can burn fat and release calories through white adipose tissues (WATs) browning. However, these studies have focused on the effect of cold stimulation that induced WATs browning while there's hardly study on the effect of hypoxia. In this study, we investigate that whether and how hypoxia contributes to WATs browning in rats from acute to chronic hypoxia. We constructed hypobaric hypoxic rat models by exposing 9-week-old male SD rats to a hypobaric hypoxic chamber for 1, 3, 14 and 28 days (Group H) under simulated environment at altitude of 5000 m. We also established normoxic control groups for each time period (Group C), as well as paired 1-day and 14-day normoxic food-restriction rats that were fed the same amount of food as the hypoxic group ate (Group R). We then observed the growth status of rats and recorded dynamic changes in histologic, cellular and molecular levels of perirenal WATs (PWAT), epididymal WATs (EWAT) and subcutaneous WATs (SWAT) in each group. Results showed that (1) Hypoxic rats had lower food intake, significantly lower body weight than control rats, and showed lower WATs index. (2) In group H14, ASC1 mRNA expressions of PWAT and EWAT in rats were lower than that in group C14, and PAT2 mRNA expression of EWAT was higher than that in both group C14 and R14. In group R14, however, ASC1 mRNA expressions of PWAT and EWAT in rats were higher than both group C14 and H14, and that of SWAT was also significantly higher than group C14. (3) In group H3, both the mRNA and protein levels of uncoupling protein 1 (UCP1) of PWAT in rats were significantly increased than group C3. And in group H14, those of EWAT in rats were significantly increased than group C14. (4) In plasma of rats, norepinephrine (NE) level was significantly increased in group H3 than group C3, and free fatty acids (FFAs) level was significantly increased in group H14 than both group C14 and R14. In group R1, FASN mRNA expressions of PWAT and EWAT in rats were down-regulated than group C1. In group H3, FASN mRNA expressions of PWAT and EWAT in rats were down-regulated while ATGL mRNA expression of EWAT was up-regulated than group C3. Conversely, in group R14, FASN mRNA expressions of PWAT and EWAT in rats were significantly up-regulated than group C14 and H14. These results suggested that hypoxia promoted different WATs browning in rats under simulated environment at altitude of 5000 m and changed the lipid metabolism in WATs. Furthermore, rats in the chronic hypoxic group showed a completely different lipid metabolism of WATs from that in paired food-restriction group.

Relevance of human fat distribution on lipid and lipoprotein metabolism and cardiovascular disease risk

PURPOSE OF REVIEW

Upper body abdominal and lower body gluteofemoral fat depot masses display opposing associations with plasma lipid and lipoprotein and cardiovascular disease (CVD) risk profiles. We review developments on adipose tissue fatty acid metabolism in the context of body fat distribution and how that might be related to adverse lipid and lipoprotein profiles and CVD risk.

RECENT FINDINGS

Recent data have confirmed the paradoxical relationship of upper abdominal and lower body gluteofemoral adiposity and CVD risk. Mechanistically, this is likely to reflect the different ways fat depots handle lipid storage and release, which impacts directly and indirectly on lipid and lipoprotein metabolism. The upper body enhances immediate fat storage pathway with rapid uptake of dietary-derived fatty acids, whereas the lower body fat depot has a reduced lipid turnover accommodating a slower fat redistribution. Body fat distribution and the fat depots' ability to undergo appropriate expansion when fat storage is required, rather than overall body fatness, appear as the important determinant of metabolic health.

SUMMARY

A focus on fat distribution in overweight people, preferably using precise imaging methods, rather than quantifying total body fatness, is likely to provide the medical community with better tools to stratify and treat patients with obesity-related complications.

Predictors of fat mass changes in response to aerobic exercise training in women

Aerobic exercise training in women typically results in minimal fat loss, with considerable individual variability. We hypothesized that women with higher baseline body fat would lose more body fat in response to exercise training and that early fat loss would predict final fat loss. Eighty-one sedentary premenopausal women (age: 30.7 ± 7.8 years; height: 164.5 ± 7.4 cm; weight: 68.2 ± 16.4 kg; fat percent: 38.1 ± 8.8) underwent dual-energy x-ray absorptiometry before and after 12 weeks of supervised treadmill walking 3 days per week for 30 minutes at 70% of (Equation is included in full-text article.). Overall, women did not lose body weight or fat mass. However, considerable individual variability was observed for changes in body weight (-11.7 to +4.8 kg) and fat mass (-11.8 to +3.7 kg). Fifty-five women were classified as compensators and, as a group, gained fat mass (25.6 ± 11.1 kg to 26.1 ± 11.3 kg; p < 0.001). The strongest correlates of change in body fat at 12 weeks were change in body weight (r = 0.52) and fat mass (r = 0.48) at 4 weeks. Stepwise regression analysis that included change in body weight and body fat at 4 weeks and submaximal exercise energy expenditure yielded a prediction model that explained 37% of the variance in fat mass change (R = 0.37, p < 0.001). Change in body weight and fat mass at 4 weeks were moderate predictors of fat loss and may potentially be useful for identification of individuals who achieve less than expected weight loss or experience unintended fat gain in response to exercise training.

Expression of inflammation-related genes in gluteal and abdominal subcutaneous adipose tissue during weight-reducing dietary intervention in obese women

Accumulation of adipose tissue in lower body lowers risk of cardiovascular and metabolic disorders. The molecular basis of this protective effect of gluteofemoral depot is not clear. The aim of this study was to compare the profile of expression of inflammation-related genes in subcutaneous gluteal (sGAT) and abdominal (sAAT) adipose tissue at baseline and in response to multiphase weight-reducing dietary intervention (DI). 14 premenopausal healthy obese women underwent a 6 months' DI consisting of 1 month very-low-calorie-diet (VLCD), subsequent 2 months' low-calorie-diet and 3 months' weight maintenance diet (WM). Paired samples of sGAT and sAAT were obtained before and at the end of VLCD and WM periods. mRNA expression of 17 genes (macrophage markers, cytokines) was measured using RT-qPCR on chip-platform. At baseline, there were no differences in gene expression of macrophage markers and cytokines between sGAT and sAAT. The dynamic changes induced by DI were similar in both depots for all genes except for three cytokines (IL6, IL10, CCL2) that differed in their response during weight maintenance phase. The results show that, in obese women, there are no major differences between sGAT and sAAT in expression of inflammation-related genes at baseline conditions and in response to the weight-reducing DI.

Femoral adipose tissue may accumulate the fat that has been recycled as VLDL and nonesterified fatty acids

OBJECTIVE

Gluteo-femoral, in contrast to abdominal, fat accumulation appears protective against diabetes and cardiovascular disease. Our objective was to test the hypothesis that this reflects differences in the ability of the two depots to sequester fatty acids, with gluteo-femoral fat acting as a longer-term "sink."

RESEARCH DESIGN AND METHODS

A total of 12 healthy volunteers were studied after an overnight fast and after ingestion of a mixed meal. Blood samples were taken from veins draining subcutaneous femoral and abdominal fat and compared with arterialized blood samples. Stable isotope-labeled fatty acids were used to trace specific lipid fractions. In 36 subjects, adipose tissue blood flow in the two depots was monitored with (133)Xe.

RESULTS

Blood flow increased in response to the meal in both depots, and these responses were correlated (r(s) = 0.44, P < 0.01). Nonesterified fatty acid (NEFA) release was suppressed after the meal in both depots; it was lower in femoral fat than in abdominal fat (P < 0.01). Plasma triacylglycerol (TG) extraction by femoral fat was also lower than that by abdominal fat (P = 0.05). Isotopic tracers showed that the difference was in chylomicron-TG extraction. VLDL-TG extraction and direct NEFA uptake were similar in the two depots.

CONCLUSIONS

Femoral fat shows lower metabolic fluxes than subcutaneous abdominal fat, but differs in its relative preference for extracting fatty acids directly from the plasma NEFA and VLDL-TG pools compared with chylomicron-TG.

A case-control study evaluating the association of purposeful physical activity, body fat distribution, and steroid hormones on premenopausal breast cancer risk

The objective of this case-control study was to investigate the relationship between purposeful physical activity, body fat distribution, body mass index, and steroid hormones. These factors are known to be implicated in modulating breast cancer risk in premenopausal women. A total of 112 newly diagnosed, premenopausal breast cancer patients and 106 age-matched premenopausal disease-free controls were admitted to the study. Information regarding personal, medical, hormonal, and reproductive history, smoking and alcohol use, physical activity history, and anthropometric measurements was obtained. Serum samples for steroid hormone assays were collected and analyzed. Disease-free premenopausal controls had a significantly higher physical activity index (PAI) (p</=0.05), however, significantly higher weight (p</=0.05), body mass index (BMI) (p=0.01), waist (p</=0.005) and hip (p</=0.05) circumferences, waist:hip ratios (p</=0.05), and serum total estradiol levels (p<0.0005) were observed in cancer cases. The final model using stepwise logistic regression analysis indicates that the variables that significantly predicted breast cancer risk were waist:hip ratio (odds ratio [OR]=1.11, p</=0.005) and serum total estradiol levels (OR=1.03, p</=0.0001). Our study provides some evidence that purposeful physical activity may reduce upper body fat distribution associated with adult weight gain. This may be a result of alterations in the steroid hormone pathway, such as reduced estradiol levels. This demonstrates the potential mechanism through which increased physical activity can reduce the risk for breast cancer in premenopausal women.

Adipose tissue and the immune system

Adipocytes anatomically associated with lymph nodes (and omental milky spots) have many special properties including fatty acid composition and the control of lipolysis that equip them to interact locally with lymphoid cells. Lymph node lymphocytes and tissue dendritic cells acquire their fatty acids from the contiguous adipocytes. Lymph node-derived dendritic cells suppress lipolysis in perinodal adipocytes but those that permeate the adipose tissue stimulate lipolysis, especially after minor, local immune stimulation. Inflammation alters the composition of fatty acids incorporated into dendritic cells, and that of node-containing adipose tissue, counteracting the effects of dietary lipids. Thus these specialised adipocytes partially emancipate the immune system from fluctuations in the abundance and composition of dietary lipids. Prolonged, low-level immune stimulation induces the local formation of more adipocytes, especially adjacent to the inflamed lymph node. This mechanism may contribute to hypertrophy of the mesentery and omentum in chronic inflammatory diseases such as HIV-infection, and in smokers. Paracrine interactions between adipose and lymphoid tissues are enhanced by diets rich in n-6 fatty acids and attentuated by fish oils. The latter improve immune function and body conformation in animals and people. The partitioning of adipose tissue in many depots, some specialised for local, paracrine interactions with other tissues, is a fundamental feature of mammals.

Integrative physiology of human adipose tissue

Adipose tissue is now recognised as a highly active metabolic and endocrine organ. Great strides have been made in uncovering the multiple functions of the adipocyte in cellular and molecular detail, but it is essential to remember that adipose tissue normally operates as a structured whole. Its functions are regulated by multiple external influences such as autonomic nervous system activity, the rate of blood flow and the delivery of a complex mix of substrates and hormones in the plasma. Attempting to understand how all these factors converge and regulate adipose tissue function is a prime example of integrative physiology. Adipose tissue metabolism is extremely dynamic, and the supply of and removal of substrates in the blood is acutely regulated according to the nutritional state. Adipose tissue possesses the ability to a very large extent to modulate its own metabolic activities, including differentiation of new adipocytes and production of blood vessels as necessary to accommodate increasing fat stores. At the same time, adipocytes signal to other tissues to regulate their energy metabolism in accordance with the body's nutritional state. Ultimately adipocyte fat stores have to match the body's overall surplus or deficit of energy. This implies the existence of one (or more) signal(s) to the adipose tissue that reflects the body's energy status, and points once again to the need for an integrative view of adipose tissue function.

Insulin resistance, impaired postprandial lipid metabolism and abdominal obesity. A deadly triad

OBJECTIVE

To review three 'emerging risk factors' for coronary heart disease, the physiological and pathophysiological mechanisms involved, and their inter-relationships.

BACKGROUND

Classical risk factors for coronary heart disease cannot adequately explain the high incidence of this disease. Abdominal obesity and impaired postprandial lipid metabolism have long been recognised as associates of coronary heart disease but only relatively recently has their importance as risk markers been established. Insulin resistance is now often seen as a common theme underlying many factors predisposing to coronary heart disease (CHD).

MECHANISMS

The mechanisms by which each of these markers relates to coronary heart disease may have common aspects. Specifically, they are all associated with a characteristic dyslipidaemia involving elevation of plasma triacylglycerol concentrations, reduction of high-density lipoprotein cholesterol (HDL-cholesterol) and the presence of small, dense low-density lipoprotein particles that may carry particular risk of atherogenesis. Insulin resistance is also associated with hypertension and impairment of endothelial function, and with a procoagulant state.

TREATMENT

No specific or separate pharmacological treatment of any of these conditions separately has been shown to reduce the risk of CHD although each can be manipulated. Lifestyle modification, with increased physical activity and dietary change, may offer the best hope of primary prevention but to achieve this, interventions at government level rather than advice from individual physicians would probably be required.

CONCLUSIONS

Abdominal obesity, impaired postprandial lipid metabolism and insulin resistance are all inter-related risk markers for CHD. They seem to reflect lifestyle in the developed and developing worlds and perhaps modification of lifestyle holds the greatest hope for their amelioration in the future.

Android obesity at diagnosis and breast carcinoma survival: Evaluation of the effects of anthropometric variables at diagnosis, including body composition and body fat distribution and weight gain during life span,and survival from breast carcinoma

BACKGROUND

Although a large body of research exists concerning pathologic prognostic indicators of the rate of incidence and survival from breast carcinoma, to the authors' knowledge very few studies have examined the effects of anthropometric variables such as height, obesity, weight gain in adulthood, timing of weight gain, and body composition to survival, although these variables are related to the incidence rate.

METHODS

The survival status of 166 patients diagnosed with primary breast carcinoma and followed for at least 10 years was obtained from the Cancer Center's registry, and significant anthropometric and other known prognostic indicators regarding survival after diagnosis were determined by Cox proportional hazards analysis.

RESULTS

Eighty-three of 166 breast carcinoma patients (50%) with up to 10 years of follow-up died of disease. Android body fat distribution, as indicated by a higher suprailiac:thigh ratio, was a statistically significant (P < 0.0001) prognostic indicator for survival after controlling for stage of disease, with a hazards ratio of 2.6 (95% confidence interval [95% CI], 1.63-4.17). Adult weight gain, as indicated specifically by weight at age 30 years, was a statistically significant (P < 0.05) prognostic indicator for survival with a hazards ratio of 1.15 (95% CI, 1.0-1.28). In addition, the authors observed the Quatelet Index, a negatively significant (P < 0.01) prognostic indicator for survival with a hazards ratio of 0.92 (95% CI, 0.87-0.98). Other markers of general obesity such as weight at diagnosis, percent body fat, and body surface area were not significant markers influencing survival. Similarly, height; triceps, biceps; subscapular, suprailiac, abdominal, and thigh skinfolds; waist and hip circumferences; family history; and reproductive and hormonal variables at the time of diagnosis showed no apparent significant relation to survival.

CONCLUSIONS

The results of the current study provide some evidence that android body fat distribution at diagnosis and increased weight at age 30 years increases a woman's risk of dying of breast carcinoma.