Jessica Ennis-Hill

Calories: 1,749

Exercise: 6 hours a day

The now retired Ennis-Hill trained almost twice as much as Usain Bolt. According to Women's Health, she mixed up her routine to "surprise" her body, from circuit training including crunches, press-ups, jumps, planks, and dips to sprints.

The gold medal heptathlete also walks her dog as part of her exercise routine, according to Ladbrokes.

In terms of diet, her breakfasts are made up of the likes of toast, cereal, or granola with yogurt and juice, fruit or cereal bars for a mid-morning snack, sandwiches, pastas, salads, or soups for lunch, and chili, stir-fry, pasta, salmon, risotto, or lasagna for dinner. She even indulges in the odd glass of red wine.