If you Google "excessive body heat," you get a number of responses about medical conditions, heat exhaustion, hyperthermia and people who always feel hot. To me, it's that simple. If you feel too hot, sweaty or uncomfortable due to heat, you have excessive body heat.
Some common causes include:
Hot environmental temperatures
Side effects of medication
Stress or Anxiety
Foot and Drink (often spicy)
Read more at: https://www.healthline.com/health/why-am-i-always-hot
I also think there is more to it than that. I think some people are simply more intolerant to heat than others. That's why some people are far more uncomfortable in the heat, while others are far more uncomfortable in the cold. If you get too hot and you don't like it, there doesn't have to be a "common cause." You don't have to search for something that is wrong with you (although talk to your doctor if you're concerned).
Everyone has sensitivities. And they range over a wide variety of issues. The key is to finding a way to cope with yours. If you have really bad allergies, try allergy medication. If you feel too hot and uncomfortable, try a body cooling wearable such as the Cooling Cuff.