The state of obesity is definitely correlated with exacerbation of several disease states. Several systemic reviews and/or meta-analysis' noted that the state of obesity is associated with worsened symptoms and signs of Polycystic Ovarian Syndrome (PCOS), Pulmonary Function and Cardiovascular Risk, Asthma, Obstructive Sleep Apnea, Kidney function, Schizophrenia, Bipolar Disorder, Alzheimer's, worsened Breast Feeding potential and heightened risk of Pregnancy complications as well as preeclampsia, and increased risk of Colorectal Adenocarcinoma.
Several Meta-analysis' indicate that obesity is correlated with disease states and appears to be further correlated with worsened disease progression over time (when compared to leaner subjects with the same disease state)
Conversely, BMI appears to be inversely related to success of suicide attempts (although attempts in women only are positively correlated) and the evidence of BMI influencing cancer survival during chemotherapy is mixed.
The above studies establish a relationship between obesity and several disease states, but do not per se establish a causative link. However, unless the (obese/overweight) person being assessed is not the statistical norm it is possible these results would apply to them
Obesity and Activity
Sumo wrestlers tend to be a hot topic in regards to 'Health at Every Size®' due to their body mass exceeding the standards of obesity yet the strength and activity level of an average Rikishi exceeding most of the population.
In sumo wrestlers, the large amount of daily physical activity conducted in accordance with a high calorie diet and state of obesity does not appear to be enough to normalize some health parameters; Type II diabetes, triglycerides, and hypertension are still higher in highly active sumo wrestlers when compared to age-matched controls of normal BMI status. This study noted no significant differences in blood glucose or total cholesterol but worsened parameters otherwise, and it should be noted that the difference in average weight was a mere 12.2kg (88kg in control, 100.2kg in Rikishi) which is not the size many associate with a 'sumo wrestler'.
The risk of premature death is higher in sumo wrestlers when comparing the heaviest weight class against lower weight cohorts; an increase in risk of death was very significant when compared against age-matched controls, although it is hard to delineate if this is due to obesity or due to professional contact sports, some evidence towards it being weight related is an association between weight and premature cardiovascular death in NFL players of heavier weight but to a lesser extent in lighter weight NFL players. Retired NFL players also appear to be at greater risk for metabolic syndrome if their BMI is greater, and the state of obesity in athletes of this caliber is associated with hepatic damage, assessed by ALT levels.
Sumo wrestlers do tend to have a more favorable body fat composition (more subcutaneous and less visceral, which is in accordance with biomarkers for reduced risk of cardiovascular disease) but this same study also noted that it has yet to be shown that exercise interventions less than the heavily intense Sumo training confer this same theoretical protective benefit.
Using sumo wrestlers and National League American Football players as models for 'High adiposity paired with High activity', there still appear to be risks associated with the state of obesity or the high calorie diet that activity cannot compensate for completely (some compensation does seem apparent, however)
Exercise does not appear to be potent enough to normalize all health biomarkers of an obese (BMI greater than 30) person if weight loss does not also occur; this may not hold for overweight persons where the state of health is inherently more favorable (than obese age-matched persons)
According to a few studies, Health At Every Size® (HAES®) is a movement away from weight-centric thinking towards health-centric thinking, and "(addresses) the biological, psychological and sociocultural aspects of weight problem, to emphasize the importance of health and well-balanced life independently of body weight, and to improve lifestyle habits".
In overweight women who participate in HAES® intervention (support groups), it appears that a reduction in appetite precedes a reduction in calories. This (appetite reduction) is a phenomena that has been noted previously with HAES® interventions in free-living conditions. The success rate of size acceptance appears to be notable in persons who self-identify as 'chronic dieters', especially when delivered via educational platforms such as a 13-week class or Focus groups.
Health At Every Size® interventions appear to be quite effective for normalizing eating habits and reducing subjective reports of appetite, which may be mediated through a reduction in anxiety and stress associated with eating; this effect is slightly more prominent in chronic dieters