Your parents aren't helping your future by calling you names. It's not motivating or useful under any circumstances. It's just wrong. There's no child psychologist, family therapist, or parenting expert in the entire universe who would recommend that moms and dads engage in such behavior.
When your parents are in a relaxed mood, tell them how you feel when they hurl hurtful labels at you such as lazy and fatty. Use “I messages” so they don't get defensive: “I feel hopeless/angry/sad/disrespected when you call me that. What can we do to stop the name-calling and solve our problems in a constructive way?” (You may want to tell them about the latest research in neuroscience that shows name-calling can alter a child's brain structure and lead to serious issues in the future such as drug addiction).
Stressed out moms and dads often resort to name-calling because they don't have the time, patience, and tools to parent correctly. Name-calling is fast, easy, and maybe familiar if that's what they were subjected to as kids. Having productive conversations and problem-solving sessions take time and effort and require knowledge and skill.
If your household is stressful (as many are), think about ways that you can eliminate some of the burden from your parents. Take responsibility for what you need to do such as cleaning your room and doing your schoolwork. When you see that your mom and dad are overwhelmed, ask how you can help.
Name-calling in a family is typically a symptom of a much bigger problem. Talk to an ally (a grandparent, a teacher, a neighbor, a school counselor) about what's going on at home. It sounds like you and your parents could use some support and may benefit from family therapy.