I love going high weight, low reps to build strength. But it is almost summer, so I want to eat lean food and be a little healthier. Do I have to switch to low weight high reps to define? Or will dieting and cardio be enough if I continue to use high weights. Thank you for the time.
Continuing to train with heavier weights is essential while on a diet. If you do not give your muscle and strength abilities a stimulus to be maintained, then it wont be. Having muscle is metabolically costly. As such, on a diet your body would prefer to get rid of that first in order to effectively provide enough energy. By using heavier weight, you give your body a reason to maintain any muscle that you have gained, and you're likely to maintain or even increase your strength.
That's not to say that you can't do other types of training as well. Metabolic resistance training seems to be an effective route for fat loss along with high intensity interval cardio. It seems as though combining these two types of training would be optimal for a fat loss diet, while preserving your hard earned muscle and strength, given that your also in a caloric deficit.