How do you support a friend mentally, to help him lose weight when they are only looking up to your advice?

Hi,

That's a good question there you are asking. I suggest that you figure out first the kind of advice they are looking to get from you. Give them that advice if you have or lead them to a source that will provide such advice as they are looking for. The key here is to be there for him but be willing to include help for other sources that will help you to help him. Do not be afraid to speak truth to the problem but be ever so kind. Be creative in what you use to encourage and how you encourage him. It must be always be full of fun and positive to have you around and, depending on the dynamics of the relationship you have/share there must be, establish a structure or understanding that is symbiotic, i.e that gives as much as it takes. The point is this: don't let the friendship feed off only you without any balance because any abused relationship tends to lead to a burnout. Hope this help.
Best of the best

I think the best support you can give your friends when it comes to mindset for their journey is to not enable them. Try to suggest healthier options when eating or activities that will encourage something physically challenging.

A good way to help your friend to keep a healthy mindset about losing weight is to constantly encourage them. One of the best ways of encouraging someone is by setting n example, maybe you could workout and train with them at the gym or set a schedule to go to the gym together. I'm sure your friend would enjoy that.