Legs day! I'm all into functional training, but heavy weights have their place in your training. Every now and again you need to lift beyond the comfort zone, which should challenge you physically and mentally: break a sweat, feel the burn, and you will be rewarded with results.
The 3 common mistakes which you may be making that are preventing you from achieving your goals are:
1> You skip meals, you eat irregularly and you eat portions and/or food which are not conducive to support your metabolism or blood sugar levels;
2> Cardio is your go-to: it trains your heart but it doesn't increase your metabolism, you burn as much as your cardio session lasts, and beyond that, you need to replace your calorie expenditure and you don't see dramatic results;
3> You refuse to lift weights, and if you do, you lift very light weights;
Now you just need to put 2 and 2 together:
1> Eat a decent breakfast, a relatively big lunch and a light dinner. Every meal should consist of lean protein (chicken, fish, shellfish, turkey, soy or dairy-based produce such as tofu or skim cheese), complex, leafy carbs and a small amount of good "fats" such as omega 3s and 6s. A good rule of thumb is 40/40/20 - 40% protein, 40% carbs and 20% good fats;
2> Do cardio but don't down play resistance training. Lifting weights is your true key to increasing lean muscle mass, improving bone density and lifting your metabolism - which means you burn calories even well after your training, extending into hours after.
It is that simple. Now go get it and have fun!