You do not need to eat between sets in a routine lifting session. Body stores and daily meals usually cover the demand. Carbohydrate and electrolytes become more useful when activity extends beyond roughly 60–90 minutes, is very intense, or another session follows the same day.
The short answer
For most ordinary sessions under an hour, water is enough; during-workout fueling becomes more relevant for long, hard, or repeated exercise.
Useful choices
Sports drink, gel with water, banana, dates, or familiar sports food can provide carbohydrate. For long exercise, roughly 30–60 g per hour is a common starting range, but it must be practiced.
Train the gut
A sudden large intake can cause bloating or nausea. Start low, divide intake across the session, and practice the exact competition plan in training.
What about protein and fat?
Neither is necessary during most sessions, and both can slow digestion. Real food may be useful in ultra-endurance events, but the plan must be individualized.
Practical checklist
Do not test unfamiliar food on an important training or competition day.
Adjust amount and timing to gut tolerance and session goals.
The quality of the whole daily diet matters more than one meal.
References
Nutrition and Athletic Performance — Academy of Nutrition and Dietetics, Dietitians of Canada and ACSM — https://pubmed.ncbi.nlm.nih.gov/26920240/
ISSN Position Stand: Nutrient Timing — https://pubmed.ncbi.nlm.nih.gov/28919842/