I want to lose weight but at the same time I don't want to gain any more muscle mass than what I already have. However, whenever I research exercises I could do the results always seem to show more defined muscles gained from their increase.
So what kind of exercises can one do to just lose weight without gaining muscles? [Preferably ones that don't require any special equipment]
Based on your question and the the answers you gave in the comments, it sounds like you might want to look into aerobic and endurance based exercise.
As far as your diet goes, you'll want to be in a healthy body fat range, but not so low as to show off definition in your muscles. While 10-15% body fat is probably the sweet zone for how your homones behave, you'll want to be closer to the 15-20% range (normal for men in their 20s).
There's actually a few different types of endurance related exercise, so don't think that running is your only option. You might enjoy:
Due to the nature of endurance related athletics, you will experience the following transformations:
You'll find that a great number of endurance athletes do not have large arms, and six packs are rarely noticeable.
The best answer for you is a healthy and nutritious diet.
You can achieve what you want simply by putting the right foods and drinks in your mouth and you won't have to lift a single weight or walk a single mile.
Lots of veggies, salads, some fruit, lean meats (chicken, Turkey, beef), fatty fish like salmon and trout.
Get rid of or at least cut down (significantly) on sugary drinks, alcohol, fast foods, anything high in carbohydrates - especially high GI carbs.
When cooking, use extra virgin olive oil, butter, or coconut oil. Avoid margarine.
Fat loss is made in the kitchen. You can't out train a crap diet. First and foremost, get your diet in check, and then worry about exercising if you wish.
You can try endurance sports to loose fat. To lose fat you need to do aerobic exercise for long time. The fat metabolism can't start fast. It slowly started after 30-40 minutes after the endurance exercise began. The single aerobic exercise must be one hour or more. You are going gain some muscles, but it's not going to be a lot. Mostly your muscles going to take just good athletic shape. To burn fat during endurance exercise you need to have good amount of the carbs in your blood, muscles and liver. The good news is, you are not going to be too hungry after aerobic exercise correctly done. Anaerobic exercise mostly useless for weight lose.
Weight gain (and especially muscle gain) is mostly a function of caloric intake. So if you exercise a lot and don't eat much you won't gain much weight or muscle.
Any exercise, aerobic mostly for example swimming, running, or playing sports. Now even these will increase muscle size generally speaking but not comparably to weight training because you are using your muscles in everything you do here. But the key to not putting on size is time under tension and eating at a caloric surplus to supply the muscle with to grow.
