The principles of nutrition and their application to exercise and health

1. Weight management The principles of nutrition and their application to exercise and health

2. Learning objectives By the end of the lesson you will be able to: • Define terms related to weight management to include: • Calorie • Energy balance • Negative energy balance • Positive energy balance • Basal metabolic rate (BMR) • Thermic effect of food (TEF) • Thermic effect of physical activity (TEPA) • Non-exercise activity thermogenesis (NEAT)

3. Learning objectives By the end of the lesson you will be able to: • Describe safe and effective guidelines for the rate of fat loss achievable through diet modification and exercise

4. Nutrients for energy Recap from last session: Energy intake is measured in joules (J) or kilojoules (kJ) but many people are more familiar with Calories (kcal). 1 kilocalorie (kcal) = 1,000 calories, or 1 Calorie (the energy it takes to raise the temperature of 1kg of water by 1°C). 1 kcal = 4.184 kJ Therefore, a 1000-kcal diet provides 4184 kJ.

5. Energy equations To convert kilocalories into kilojoules, multiply by 4.2. 1kcal = 4.2.kj 10 kcal= 42 kj To convert kilojoules into kilocalories, divide by 4.2. Example: If 100 g of food provides 400 kj and you need to know the kilocalories: Divide 400 by 4.2 (95 kcal).

6. Common weight management terminology • Energy balance. • Negative energy balance. • Positive energy balance. • Basal metabolic rate (BMR). • Thermic effect of food (TEF). • Thermic effect of physical activity (TEA). • Non-exercise activity thermogenesis (NEAT).

7. Energy balance Energy balance takes into account the amount of calories of food consumed (calories in) and the amount expended (calories out). Neutral energy balance – when calories taken in are equal to the calories expended. Positive energy balance – when more calories are taken in than expended, weight is gained and fat stores are increased. A common approach to reducing body fat is to establish a negative energy balance (an energy deficit) by consuming fewer calories than the amount of calories expended.

8. Basal metabolic rate (BMR) Sum total of all the reactions that occur in the body when at complete rest and no digestion is occurring. This is usually expressed as the number of calories needed to sustain basic functioning. Base level of energy needed to keep bodily functions ‘ticking over’. Comprises the largest chunk of our daily energy needs. The brain needs 600 calories a day on average.

9. Thermal effect of food (TEF) The amount of energy expended by the body through the ingestion, digestion, absorption, utilisation and storage of food, and therefore how much energy it costs the body to eat and then digest the food. In males – 6-10 % of daily energy needs. In females – 6-7 % of daily energy needs.

10. Thermal effect of activity (TEA) The amount of energy required for planned and unplanned levels of physical activity. The most variable component of energy expenditure. It accounts for approximately 20-40% of total daily energy expenditure (TDEE) – the amount of energy that the body uses up doing daily activities). We can affect the TEA by choosing high-intensity activities.

11. Non-exercise activity thermogenesis (NEAT) The energy expended for everything that is not sleeping, eating or planned physical activity or sports-like exercise. It ranges from the energy expended walking to work, typing, performing work, undertaking tasks around the home/garden and fidgeting.

12. Recap on calculating daily energy expenditure Energy intake is estimated at 2000 calories per day for women and 2500 calories per day for men. These are very basic and general guidelines that do not take into account any specific individual requirements. The Harris-Benedict equation provides a better estimate of individual daily energy needs, taking into account gender, age, height, weight and activity levels. The result does not take into consideration the amount of lean body mass, so it would not be accurate for the extremely muscular (under-estimate caloric needs) and the extremely overweight (over-estimate caloric needs).

13. TheHarris-Benedict equation Men BMR = 66 + (13.7 x weight in kg) + (5 x height in cm) – (6.8 x age). Women BMR = 655 + (9.6 x weight in kg) + (1.8 x height in cm) – (4.7 x age). (1 inch = 2.54 cm/1 kg = 2.2 lbs/1 stone = 14 lbs). Example: Female, 30 years old, 5’ 6’ tall (167.6 cm) weighing 8 stone 8 lbs (54.5 kg). BMR = 655 + 523 + 302 – 141 = 1339 calories/day.

14. TheHarris-Benedict equation Once the BMR is known, the total daily energy expenditure (TDEE) can be calculated by multiplying BMR by the activity multiplier.

15. The starvation response This response is thought to hark back to hunter-gatherer days where the body prepared in times of plenty for times of famine and vice versa. In times of dietary restriction or lack, the following occurs: • The body will utilise some body fat for energy to make up the deficit. • To lower metabolic rate, muscle mass is also ‘burned’ to provide fuel. • The body increases its ability to store fat in readiness for when food is available again. • Appetite is also heightened to drive behaviour for finding food.

16. Creating an energy deficit To avoid the starvation response we must be careful how we cause energy deficit, whether by diet alone or through diet and exercise. The ACSM advise a 250-500 kcal deficit. It is suggested that this may cause ½ lb-1lb loss per week. The NHS recommends individuals should aim to lose about 1-2lb a week by eating 500-600 fewer calories than needed per day. These rates will ensure muscle is retained and body fat is lost. Faster weight loss is usually due to loss of water and muscle, which would affect physical activity and exercise performance.

17. Creating an energy deficit A combination of diet and exercise has proven to be more successful than diet alone. Combining a 500kcal dietary deficit with increased exercise creates a much larger calorie imbalance.

18. Energy deficit task Use the Harris-Benedict equation, dietary restrictions listed and activity tables in your handout todetermine what the energy deficit would be for the following people.

19. Energy deficit task Use the Harris-Benedict equation, dietary restrictions listed and activity tables in your handout todetermine what the energy deficit would be for the following people.

20. Dietary interventions What aspects need to be considered when trying to change a diet to create a fat-loss or muscle gain?

21. Dietary interventions • Frequency of meals. • Insulin response. • Macronutrient balance. • Biochemical individuality.

22. Meal frequency Research has shown that regular meals (three per day) are recommended. • Less hunger due to more stable blood sugar. • Metabolism maintained. • More likely nutrient balance.

23. Effects of insulin Blood sugar Meal

24. Refined foods – Insulin High-GI foods: • Biscuits. • Breads. • Cakes. • Ice cream. • Sweet sauces. • Soft drinks. • Pizza. • Pasties. • Pastries. …cause a large / fast spike in blood glucose.

25. Insulin resistance • Elevated insulin leads to a fat-storing internal environment. • Elevated insulin suppresses the use of fat as a fuel. • Chronically high insulin levels lead to insulin resistance over time. • Insulin resistance is associated with high body fat levels and low activity levels.

26. Reducing insulin levels Improving diet is the most significant factor. CV and resistance work can: • Reduce abdominal body fat. • Reduce insulin resistance. • Maintain muscle mass and metabolic rate.

27. Macronutrient balance • Higher protein / fat diets should moderate carbohydrate. • Higher carbohydrate diets should moderate protein and fats. This helps to avoid the combined effect of excess calories in the presence of excess insulin.

28. Individuality • We are very different on the outside. • We are very different on the inside. • Genetics and gender can dramatically influence the type of fuels needed. • This is why different people succeed on different diets.

29. Body fat levels • A certain amount of body fat is essential for: • Protection, cushioning and insulation around organs. • Forming an essential part of the membranes in every cell in the body and in the brain, nerve tissue and bone marrow. • The minimum amount of body fat required for life is around: • 3-5% for men. • 8-14% for women*. • These ranges are classed as very low. • *Women need 5-9% more body fat than men to ensure normal hormonal and menstrual functions occur.

30. Body fat levels • Very low body fat levels are not sustainable and can be detrimental to health. • Performance in sport and physical activity suffers and women’s periods may stop, putting them at risk of additional problems, such as increased bone loss and osteoporosis. • It is difficult to come up with an exact figure of how much body fat is needed for health but this can be estimated at: • 13-18% for men. • 18-25% for women. • For competitive sportspeople, these figures tend to be lower.

31. Losing body fat There is no secret formula for losing body fat. The best way is through a combination of diet and exercise. Food intake needs to be nutritious and the diet balanced but involving a reduction in calories. Experts in the field of nutrition agree that the best way is to start by cutting out high-fat and high-sugar foods.

32. Losing body fat Why do experts recommend cutting out high-fat and high-sugar foods as the best way to begin losing body fat? Are there risks if the diet is too low in fat?

33. Reasons for cutting out high-fat foods • They are low in protein, vitamins and minerals. • Fat contains at least two-and-a-half times more energy than starchy foods or animal protein. It is therefore easy to ingest excess energy from fat through small portion sizes. • Fat in the diet is easily converted into body fat. • The body can store almost unlimited quantities of dietary fat. Only small amounts of starch foods and sugars can be stored in muscle and the liver. • Fats have a weak effect on long-term control of appetite and little impact on feeling full, which can lead to over-eating. Eating a diet that is too low-fat carries the risk of the fat-soluble vitamins not being absorbed, so a diet still needs to include the right fats.

34. Recommendations for fat loss • Carbohydrate intake should be sufficient to meet energy demands. • Protein intake should ensure satiety and prevent loss of lean muscle tissue. • Stick to the recommendations of: • Carbohydrate – 50-60% • Protein – 15-20% • Fat – 20-35%

35. Learning review • Can you now: • Define terms related to weight management to include: • Calorie • Energy balance • Negative energy balance • Positive energy balance • Basal metabolic rate (BMR) • Thermic effect of food (TEF) • Thermic effect of physical activity (TEPA) • Non-exercise activity thermogenesis (NEAT)

36. Learning review • Can you now: • Describe safe and effective guidelines for the rate of fat loss achievable through diet modification and exercise