I hear it all the time: “I’ve joined a gym, so I’ll be losing weight soon.” I then ask, “That’s great! What diet plan are you following?” and often they’ll respond with, “Oh, I’m not doing a diet. I’m going to work out to lose the weight,” or “Lots of fruits and vegetables and WeightGain 2000 (or whatever protein supplement they’re taking).”
For losing weight, there’s no exercising your way out of a bad diet. You will surely build muscle, but that doesn’t always mean you will lose weight. “Fat burning” is a myth, and you don’t actually burn fat as you exercise. You will sweat a lot, but that’s not fat leaving the body; just hydration.
If you want to lose weight, you have to change what you put into your body. Low carbs is best (which is why I advocate the Paleo Diet), but people have success with many other diets like Keto, CICO (Calories In/Calories Out), Intermittent Fasting, etc. Whatever you do, make the change, commit to it, and don’t cheat/sabotage. And for heaven’s sake, don’t think you can exercise enough to lose weight without changing your diet. You’re going to get disillusioned and quit.