How to fatten up dragon fruit branches?

[NewGen]

Are flat and/or skinny branches indicative of a lack of water? or something else?
Thanks,

[pineislander]

Even though I grow in the ground with plenty of water and fertility sometimes I have gotten flat branches but then they change back to normal 3 sided.

[spaugh]

They fatten up with age.

[Victoria Ave]

Mine fatten with water, they get fat over winter and spring with our wet winters and get skinny with hotter weather and fruit production in the summer

[NewGen]

Thanks guys. I'll water more and add more fertilizer.

[Ulfr]

As above they fatten up with age.

Although, I recently had some get very skinny in the pot after already being fat. Ended up finding grubs had eaten the roots (cicada or beetle larvae, very common here). Changed the soil and they grew back fine.