My brother is an amazing person. Has a great job, wife, family, etc.. but he's 6 feet tall and 145 pounds and in his mid 30's. He just got back into weight-lifting by re-starting his adjustable dumbbell program and he texted me this pic earlier of his workout today.

I don't want to give him a firehose of information as I watch/listen to about 2 hours of fitness & hypertrophy videos per day. His motivation is also very fickle and I absolutely do not want for my advice to make him feel like he needs to push himself too hard (his burnout risk is high). He also has been thin his whole life and says he wants to put on more weight but he always goes back to his old eating habits after 2-3 weeks and loses any weight that he gained.

Muscle growth is metabolically expensive so should I just recommend that he train only 1-2 muscle groups (such as shoulders and biceps) if I'm 100% confident he won't eat more?

He is motivated enough to try but his effort is mostly wasted since he doesn't want to invest into a real gym membership because he had a nightmarish experience trying to cancel his old gym membership 5 years ago so that ship has metaphorically sailed. He also doesn't eat enough calories nor protein.

What am I missing? I feel like there's some helpful advice I could probably give him but I'm unable to figure out what to tell him that he should mostly focus on (since he's still a beginner). Any/all recommendations for how to traverse this situation/opportunity would be greatly appreciated. 💪