Eat lots of African starch foods like meals from corn, yam, cassava and millet with lot of meat.

Vitamin B12 is a very good energy supplement.
As far as weight loss and muscle building goes you might want to try to cut out or decrease consumption of simple carbs (bread, pasta, potatoes), increase consumption of protein and complex carbs (fresh fruits and vegetables) and definitely go as low-fat as possible. Don't eat out - there's more fat there than one can count withough being horrified. And of course exercise, both cardio and strength-training. Strength-training is of course key to muscle mass increase.

I'm pretty sure I was told that proteins are good for those things. I know they're good for muscle building. Also, it was prescribed by a doctor once when I had a severe lack of energy. And I'm told it's good to lose weight.