Eating 1,000 calories a day often leads to weight loss. However, regular exercisers likely need more than 1,000 calories a day to lose weight at a safe but effective pace. The National Heart, Lung and Blood Institute suggests that active women and men avoid dropping below 1,200 calories a day during weight loss.owever, regular exercisers likely need more than 1,000 calories a day to lose weight at a safe but effective pace. The National Heart, Lung and Blood Institute suggests that active women and men avoid dropping below 1,200 calories a day during weight loss.