(7/7) My key takeaway here is that ANY of the prescribed dietary changes had a modest effect on weight loss (though more loss would be better!). While these diets aren’t used as often now, the lesson for patients is that the best weight loss diet is the one they can STICK TO!.

(6/7) Finally, a major point here is that weight loss directly correlates with compliance (more compliant = more weight loss). Perhaps a boring finding, but important to the big picture:

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(5/7) Now for weight loss. In all groups, weight loss was present at 1 year (figure below). Weight loss ranged from 8.6 to 14.6 lbs. BUT there was no difference between the groups (P=0.4). Data not shown, but cardiovascular markers (e.g. LDL, insulin, CRP) went down a bit.

(4/7)Starting with adherence, the below figure shows adherence by diet (Y axis) over time (x axis). 10 is perfect 1 is none. This shows something that many of us know: adherence to a diet goes down over time!

(3/7) Primary outcomes were weight change and cardiac risk factors (labs). They also looked at adherence.

(2/7) In the study, 160 participants were randomized to 1 of 4 diets:. 1. Atkins (low carb).2. Zone (macro targets).3. Weight watchers (calorie restrict).4. Ornish (fat restrict). Bit of a blast from the past, huh?.

(1/7) Next in our obesity series: Lets dive a bit more into how diet can affect weight loss. Here is a 2005 paper from Dansinger et al. in JAMA that examines the effect of 4 different diets on weight loss and cardiovascular risk factors at 1 year:.

(7/7) Putting this together, beyond my (somewhat nerdy) interest, it has implications for obesity!. Therapeutic targets (or lifestyle interventions) that increase BAT may offer a way to combat obesity (though would always need to consider their effects on raising body temp!).

(6/7) Interestingly, the authors correlated BAT presence (yes/no) with clinical factors. Increasing age, BMI and blood sugar level were INVERSELY associated with BAT. Patients in cold temperatures also had more BAT.

(5/7) As to results, as shown below, BAT is found in men and women, though at low prevalence (3.1% men, 7.5% women). It’s more common and more metabolically active in women.

(4/7) Here, the authors leveraged a recent (at the time) description of FDG-PET-based imaging to show BAT. Measurable fat deposits with uptake are putative BAT (see below images of neck/thorax – bright is the fat). They set out to analyze 1,972 PET scans for presence of BAT

(3/7) Traditionally, BAT was not believed to be found in adults. Even when present, it was in very small amounts. BUT, even a little BAT matters, as a very tiny amount of active BAT could account for up to 20% of human daily energy expenditure!.

(2/7) What is BAT? It’s fat, but different! . It regulates energy through a protein called UCP1. This protein “uncouples mitochondria respiration,” generating HEAT. Newborns rely on this. However, it’s also been shown to affect obesity risk in mice :.

(1/7) Paper five in our obesity and prostate cancer series: here we will examine a 2009 NEJM paper on a topic I've always found fascinating+somewhat mysterious: brown adipose tissue (BAT).

(6/6) To conclude, this is a landmark study showing that there's a strong genetic component to obesity. However, take heart, as environmental factors do exist (giving hope to physicians trying to counsel obese men with prostate cancer…). Though, it is a striking finding!.

(5/6) Results are below. Bottom line: there was a strong association between adoptee weight and BIOLOGICAL parent weight (i.e. larger adoptees had larger biological parents [P<0.001 for mothers, P<0.02 for fathers]) while there was no relation with adoptive parent weight.

(4/6) Adoptees were broken down into four classes (thin, median, overweight and obese) as shown below. The authors then evaluated if adoptee weight class was associated with the weight class of biological and/or adoptive parents.

(3/6) They leveraged data from the Danish Adoption Register, which has detailed information for non-biologic adoptions for three groups: .1) adoptees (i.e. those NOT raised by their biological parents).2) adoptive parents, AND .3) the biological parents (!).

(2/6) Here, the authors dove into a classic “nature vs. nurture” question using an elegant approach to evaluate the effects of genes vs. the environment….

(1/6) Paper two in our prostate cancer and obesity series:. Let’s head back a bit in time to a paper from 1986 in the NEJM looking at the genetics of obesity:.