Transcript Nutrition
Nutrition Learning Objectives: 1. To be able to explain BMR, Body Fat Percentage and Obesity. 2. To know the 7 classes of food and their role in a healthy diet. 3. To understand the dietary needs of various athletes. Energy • The amount of energy needed depends on activity levels and basal metabolic rate (BMR). • BMR is the rate at which a person uses energy. It depends on gender, age and physique. • Young people have high BMR due to their growth and development. • Men usually have a higher BMR due to greater muscle mass. • BMR accounts for about 75% of our energy needs. Percentage Body Fat • Ideally, energy intake should equal energy required. • Any excess energy taken in will be stored as fat. • On average men have 10-20% body fat and women 15-25%. • Body fat % can be measured by: skinfold measures, bioelectrical impedance or water submersion. Obesity • Obesity is a condition where a person’s percentage body fat is over 40% or when their BMI is above 30. • BMI (body mass index) is your height to weight ratio. • A BMI above 40 is strongly linked to a range of diseases including cancer, heart disease, diabetes and high blood pressure. • Causes include inactive lifestyles, inactive jobs, and overeating. Overcoming Obesity • Overweight individuals often find it difficult to be physically active. • The Department of Health recommends at least 30 minutes of exercise 5 days a week. • Only 37% of men and 25% of women do this. • A lack of physical activity among children is an increasing growing problem. 7 Classes of Food Carbohydrates – provide the body with energy. Fat – used as an energy source during rest and low intensity exercise. Protein – used for growth and repair and a minor energy source. Fibre – helps the digestive system. Minerals – required for functions such as bone growth, energy metabolism and nerve function. Vitamins – complex substances with a variety of functions including energy metabolism and tissue formation. Water – essential for functioning of nearly all cells. Carbohydrates • Carbohydrates are converted to glucose to provide energy. • Excess glucose is stored as glycogen in the liver and muscles (and then fat when stores are full). • High levels of activity will use up the available glucose, then stored glycogen and fat. • Carbohydrates are found in potatoes, bread, rice and pasta. Fat • Fat is made up from fatty acids and glycerol. • Triglyceride is a simple fat found in adipose (fat) tissue and muscle. • Fat contains more than double the energy of carbohydrates. • Fat requires large amounts of oxygen to break it down and so can only be used for low intensity exercise. • Fat is also a carrier of fat-soluble vitamins. • High fat intake (particularly saturated fat) has been associated with raised blood cholesterol level and heart disease. Protein • The building block of proteins are amino acids. • Protein is needed for growth and repair. • Athletes in strength and power-type activities will be repairing and developing muscle tissue. • Protein is found in meat, fish, eggs, milk, nuts. Fibre • Fibre acts as a bulking agent and prevents constipation. • It is often a part of the diet that is neglected. • Fibre is found in whole-grain and high-fibre cereals. Minerals Minerals are required for a variety of functions and include: • Calcium – formation of bones and teeth. Found in milk and cheese. • Magnesium – required for energy metabolism and electrolyte balance. Found in grains and nuts. • Sodium – helps regulate water content, electrolyte balance and nerve function. Excess sweating causes sodium depletion whilst too much salt in the diet is linked to high blood pressure. • Potassium – essential for water and electrolyte balance. Found in fruit and vegetables. • Iron – required for haemoglobin in red blood cells and to aid the immune system. Found in broccoli and Guinness! Vitamins Complex substances needed in small amounts for many functions. Fat soluble vitamins include: • Vitamin A – essential for skin and mucous membranes, as well as the immune system, vision and normal growth. Found in liver, milk, cheese. • Vitamin D – works as a hormone controlling the amount of calcium absorbed by intestine as well as bone structure. Found on oily fish, eggs, the sun. • Vitamin K – essential for clotting blood. Found in meat and veg but also made in the gut. Vitamins (cont…) Water soluble vitamins include: • Vitamin C – involved in production of connective tissue (skin, cartilage, bone) as well as the function of blood vessels. Found in oranges. • Vitamin B1 – needed for release of carbohydrate. Found in whole grain, nuts, pork. • Vitamin B2 – needed to release energy from protein, carbs, fat. Found in milk, eggs, cereal. (and several more; see textbook for details) Water • Over half the body consists of water and all living cells depend on it. • Provides the medium in which most reactions in body occur. • Acts as lubricant for joints and eyes. • Helps to regulate body temperature. • Amount required depends on age, climate, diet, activity levels. • Dehydration can cause impaired physiological responses, lower performance level and fatigue. • Water replacement is essential before, during, and after exercise. Isotonic drinks can replenish water and carb levels more quickly. Balanced Diet • A balanced diet is one which contains sufficient amounts of the nutrients required by the individual. • For most, eating a more balanced diet means: eating more fruit and veg, eating more starchy food (bread, potato, rice, pasta), eating leaner meat and less fat. Benefits of Physical Activity Physical activity has been shown to have numerous benefits including: • Reducing risk of cardiovascular disease, high blood pressure, diabetes, obesity and cancer. • Improves mental wellbeing, strengthens skeleton and maintains a healthy weight. • Promotes strength, coordination and balance. Different Diet for Athletes • Marathon runners need greater amounts of carbohydrates in order to provide energy for prolonged periods. • They also require greater amounts of fat to save carb stores and because endurance training leads to greater fat metabolism. • Any athlete will need greater levels of vitamins and minerals due to an increased metabolism level. • Power/strength performers will also need greater protein intake because of the need for muscle repair and growth.