<human>: we've been together for a year, he's living 400 km away from me so we see each other every 2- 3 weeks. We recently had some trouble, he was having doubts about us but then changed his mind and states that he does really love me. 
Last night while skyping he told me "you were skinnier this summer, that used to suit you better, don't get fatter that you are now".
I took 3 kg (6.6 lbs) in the last 6 months (hard new uni, problem with friends, new job, new rythm..) 
i've never been skinny or specially fit and I don't think that i will ever be. I used to go to the gym 3 times a week (i loved to go cause i was just going for myself, because i felt no pressure nor obligation to go) and he even got into it himself because he admired how much i liked it. But for the last 3 months I've stopped going.

He told me that he keeps on telling me to go to the gym but that if i don't go he feels that i don't take him seriously. 
Since he said that i feel that just want to give me orders, to oblige me to change and it kills all motivation.

I understand his point but i don't like his approach to it. How could he approach it to me in a more tactful way?

(please excuse my poor english)

Give me a shortened version of the text
<bot>: Boyfriend thinks i got fat, and that I don't take him seriously if i'm not going to the gym when he tell me to. How could he approach it to me in a more tactful way?