AQA GCSE Food Preparation and Nutrition: Revision Guide

Food Safety > Food spoilage and contamination Nutriti nal needs and health Effects of a de ciency of energy in the diet • Body loses weight as fat stores are used up • Fat stores are gradually used up, so it takes time for weight loss to happen • This is the basis of weight reducing diets, which should be followed in a controlled way so that not too much weight is lost Effects of an excess of energy in the diet • Energy is stored as body fat • The weight of the body gradually increases • Obesity may be the result of continuous excess energy in the diet • Gradual weight gain The amount of energy needed each day The recommended amount of energy from different nutrients each day is: • Carbohydrate: 50% • Fat: 35% or less • Protein: 15% • For carbohydrate, most energy should come from starch and intrinsic sugars (naturally found in foods, e,g, vegetables and milk) • No more than 5% should come from fruit sugars, e.g. fruit juice and free sugars (added to foods) What affects the amount of energy needed by the body The amount of energy needed is influenced by: • A person’s metabolic rate • How active someone is To stay at a healthy weight, the body needs to be in energy balance: Basal metabolic rate (BMR): • Amount of energy needed to keep us alive and the body working normally • Varies according to age, gender, body size, physical activity level Physical activity level (PAL): • Physical activity reduces risk of developing a range of diet-related diseases, e.g. obesity and heart disease • Improves strength of skeleton and muscles • Keeps brain alert Energy balance: • The amount of energy consumed in food must be used up by the BMR and PAL • Too much energy consumed leads to weight gain • Too little en e rgy consumed leads to weight loss Energy dense: a food that contains a lot of fat and/or carbohydrate and has a high energy value BMR: Basal metabolic rate is the amount of energy we need to keep our body alive PAL: this means physical activity level, and is the amount of energy we use for movement and physical activity every day Energy balance: the amount of energy we get from food each day is the same as the amount of energy we use each day Key terms you should try to use in your answers Applying your learning Many school-aged children and teenagers in the UK have been identi ed as being overweight or obese. • Give two reasons why the numbers of school-aged children and teenagers becoming overweight and obese have signi cantly increased in recent years. • Describe two likely long-term effects on the health of these children and teenagers if they remain overweight or obese. • Suggest three ways in which children and teenagers can avoid becoming overweight or obese, giving reasons and examples in your answers. energy energy used Balanced weight eaten energy used Weight gain energy eaten energy eaten energy used Weight loss 32 6