Good diet to lose weight and build muscle?

Building muscle whilst losing weight at the same time is very difficult, it requires a good balance of calorie control and weight training. You need to maintain a calorie deficit of about 500, lower than that and your body probably won't be willing to put on muscle. So you need to calculate how many calories you're burning in a day, including all the exercise/physical activity you're doing, and subtract 500 from the amount, that is how many calories you should be eating. Doing this will allow you to lose 1lb of body fat a week.

Within this calorie limit, you need to be eating 177g of protein every day, this is vital, if you don't have a high protein intake, you're just gonna burn muscle tissue. Having protein every 3 hours helps, but isnt vital, but it is vital that you're getting protein for breakfast, before bed, before your workout, and immediately after your workout. Also, don't be afraid of healthy fats, you need them. It's carbohydrates you'll be mainly limiting, having most of them before and after your workout.

Here are some vital compound lifts for any muscle building routine:

Squats (works the entire body)
Deadlift (works mainly legs and back)
Bench Press (works mainly chest, shoulders, and triceps)
Overhead Press (works mainly shoulders, triceps, and chest)
Pull-ups/chin-ups (works mainly back and biceps)

Here's a routine I recommend:

Monday
Squat 3x5
Bench press/Overhead press 3x5 (alternating)
Chin-ups: 3 sets to failure or add weight if completing more than 15 reps

Wednesday
Squat 3x5
Overhead Press/bench press 3x5 (alternating)
Deadlift 1x5

Friday
Squat 3x5
Bench press/Overhead press 3x5 (alternating)
Pull-ups: 3 sets to failure or add weight if completing more than 15 reps

3x5 means 3 sets of 5 reps. Start with very light weight to learn proper form. Increase weight by 2-5kg on exercises each workout. Add 3 sets of abdominal exercises at the end of each workout if you like. When the weights get heavy, do progressively heavy warm-up sets to reach your working weight.