Which condition can result from very heavy perspiration or serve diarrhea?

Electrolyte imbalance.

Explanation: Perspiration and diarrhea can lead to the loss of essential electrolytes, such as sodium, potassium, and magnesium. This can disrupt the body's fluid balance and cause a variety of symptoms, including muscle cramps, nausea, vomiting, and fatigue. In severe cases, electrolyte imbalance can be life-threatening.