The answer to the question whether you should lose weight or build muscle first will depend on your specific issue on fat and how much of it you have. The bottom line is that if you are obese then you should definitely lose weight before you start to build muscle.
The definition of obesity is over 25% to 30% body-fat and this is the only exception when it comes to deciding to lose weight or build muscle first. The reason that it is the exception is that the general rule for losing weight or building muscle should be to build muscle first before losing weight.
If you are not obese then losing weight will not show your abs or the muscle that you do not have simply because you do not have any. When you get stronger by lifting weights you will put on muscle all over your body by doing compound exercises like squats and deadlifts.
This means that your abdominal cavity will get thicker as you get stronger and it will start to show itself whether you are overweight or not. The same can be said for the muscles in your upper and lower body as these muscles will show the increase in strength that you are getting by becoming larger.
It will obviously not happen overnight and you need to change your habits and start avoiding the eating patterns that got you overweight in the first place. This might take a bit of research online but the information is freely available on how to eat correctly and what to eat and when to eat.
But your objective is to start training first and start putting on quality muscle by getting stronger and changing your daily habits. Only when you have started to see that you are into a regular routine should you start to think about losing that fat which is hiding your muscle that you have worked so hard for.
When deciding to start training you need to start with the basics and that means compound exercises which are designed to get you strong. The most important aspect of doing these compound exercises is doing them the correct way with the correct form and technique.
In conclusion if you are not obese which means a body-fat of over 25% then you should first start training to build muscle before you start trying to lose that excess weight/fat. There are very specific guidelines that will guide you to the exact way to go about it and how to count calories.
Once you have started getting into the daily routine of training on a regular basis of at least three times a week you can start looking at the many weight-loss options out there. Counting calories has proven itself to be very effective but that does not mean that there is not another way to lose weight effectively.