The insulin-sensitive person has clearly been able to grow new fat tissue as evidenced by the many small adipocytes you see in the picture, meanwhile the insulin-resistant person has fewer and larger adipocytes, the in-ability of fat tissue to grow is causing insulin resistance.
Because large bloated adipocytes are themselves more insulin resistant, which means less glucose uptake and less production of the lipokine palmitoleate. This lipokine released by adipocytes is what keeps whole-body insulin sensitivity good ( glucose uptake by adipocytes is also defined as "good" insulin-sensitivity ). Dont worry if your gaining weight in the mean-time, so long as you can stay insulin sensitive so that you can keep guzzeling down loads of that cheap glucose we're selling, gotta keep our consumerism society going you know.......
I suspect the person on the left, the insulin sensitive individual, with all his nice new small adipocytes, would have a SIGNIFICANTLY harder time trying to lose weight if he did ever diet.
Oh and I just spotted this little gem in the discussion of the same paper....
It has recently been demonstrated that adipocyte number is a major determinant for fat mass in adults ( link )
This is as I said on Guyenet's other post, but I was larger ignored or challenged.
To me its clear, fat cell number determines your "body-fat" setpoint. The more fat cells you have, the fatter youll be. period.
And as I also have posted on previously, this convinces me more than ever that the only true cure for obesity is adipocyte apoptosis.