# Energy Balance and Body Weight

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Energy Balance and Body Weight

To maintain a healthy body weight we need to balance the energy we take in (food) with the energy we expend . This balance is specific to each individual. Children and teens need to consume more nutrients and energy because they are still growing.

Energy Equation Energy storage= Energy intake- Energy output
This equation shows the amount of excess energy stored by our body. When too much or too little energy is consumed problems can arise that may hinder athletic performance and possibly have negative health consequences. Factors that affect the equation: caloric intake, physical activity and the rate our body burns energy.

Calorie count Calorie is a measure of heat. It is the amount of energy needed to raise the temperature of 1 gram of pure water by 1°C. In food context a calorie (a food calorie) is a kilocalorie ( 1000 calories). This is a measure of how much energy food will produce as it is processed by the body. 1 food calorie = 4184 joules (4.184KJ)

The the three energy nutrient types supply calories in different amounts.
1 gram of carbohydrates = 4 calories 1 gram of protein = 4 calories 1 gram of fat = 9 calories Food high in calories provide a lot of energy. When that energy isn’t used it gets stored in the body mostly as fat. Fat is the preferred way to store energy because it is the most dense macronutrient.

Daily Caloric Need Is the number of calories necessary to maintain body weight. 3 factors contribute to our daily caloric need Basal metabolic rate (BMR) The thermic effect of food (energy needed to digest and absorb food) Calories needed to to fuel activity

When less energy is consumed than expended a decrease in body weight will be the result
This is a negative energy balance. A positive energy balance would be if you consume more energy than expended resulting in weight gain The proportion of macronutrients ( fat, carbs and protein) affects your caloric balance. 45-65% - Carbs 10-35%- protein 20-35%- fat

Estimating Daily Caloric Need Based on RMR
Metabolic rate (MR) measures energy that must be consumed in order to sustain essential bodily functions: heartbeat, breathing nervous system, etc. Additional calories would be needed depending on physical fitness, age, gender, weight, lean muscle mass.

BMR vs. RMR Basal metabolic rate (BMR) is a measurement under vigorous (laboratory) conditions hours after last meal with individual at rest but not asleep. Resting metabolic rate (RMR) is an estimate of metabolic rate under less rigorous conditions.

Harris- Benedict Equation
Males: RMR= (5xH) + (12.7x W) – (6.8xA) Females: RMR = (1.9xH) + (9.5xW) – (4.7xA) W= weight in Kg H= height in cm A= age in years

Now you need to multiply by the appropriate “activity factor”.
Sedentary (little to no exercise) RMR x 1.2 Little activity (1-3 days a week) RMR x 1.375 Moderate activity ( 3-5 days a week moderate exercise) RMR x 1.55 Very active ( hard exercise 6-7 days) RMR x 1.725 Extra active ( very hard daily exercise) RMR x 1.9

Effect of Exercise on Fat loss/ Muscle Gain
When it comes to losing weight eliminating fat from your diet is not the most effective way of losing weight. The total amount of calories consumed will determine whether or not most people will gain or lose weight. If someone were to exceed the caloric need by 500 calories for 7 consecutive days their caloric gain for the week would be 3500 calories 500 calories x 7 days= 3500 calories

Reducing calorie consumption and an increase of exercise would result in weight loss of 3500 calories. 3500 calories = 1 pound of fat By losing weight you also could be losing tissues such as muscle. To stop this from happening you should do resistance training.

For those who do resistance training they may not notice any drop in weight. But may be losing body fat. As an athlete or someone that does resistance training it is important to find out your body fat percentage and set realistic goals from there. A gradual weight loss program ensures maximal fat loss but preserving muscle tissue.

Should being underweight be a concern?
For some people being underweight can be a serious health issue. It is a concern when they experience fatigue, frequent, illness, impaired concentration, intolerances to cold and apathy. If someone obsesses over food and weight, voluntary restricts food intake and takes part in excessive exercise, an eating disorder may be present and the individual needs to seek medical attention

Female Athlete Triad Is a combination of disordered eating, amenorrhea and osteoporosis.

Disordered eating If low energy diets persist one can experience: reduced immune function, decreased energy levels, and stunt growth. In active women reproductive function and bone formation begin to be suppressed when energy availability is below 30%.

Amenorrhea Is the absence of the menstrual period. It is divided into 2 categories. Primary amenorrhea is when a female hasn’t started menstruating by age 15. Secondary amenorrhea is when a woman stops menstruating for more than 3 months consecutively. Exercise has no effect on the menstrual cycle. It occurs because the body doesn’t have enough energy left to sustain reproductive function.

Low Bone Mass Low energy availability suppresses estrogen and other metabolic hormones. The result is an increased rate of bone breakdown and prevents bone formation. Bone mass in young adults is a major determinant of bone fractures later in life. Untreated menstrual disturbances and low energy availability can result in reduced bone mineral density and possibly osteoporosis.

Nutrition for Optimal Performance

As an athlete you should be modifying the Canada’s food guide to meet your nutritional needs.
Depending on the intensity of the activities you do your macro-nutrient goals will be different. For most athletes nutritionist recommend: 55-65% from carbs, 10-15% from proteins and 25-30% from fats.

Nutritional timing Timing of nutrient intake is very important for athletes to not only recover from training but also to perform at an optimal level.

Pre- Exercise Nutrition
The purpose of any meal consumed before training is to minimize fatigue and to make sure the body has enough carbohydrates in the muscle and liver. The meal should be eaten 3-4 hours prior to activity. The meal should be familiar to the athlete. The meal will be high in complex carbohydrates and low in fat and fibre. Large amounts of protein should be avoided and portion size should be small to medium size.

During Exercise Nutrition
Staying hydrated is one of the main goals athletes should achieve during training. For activities lasting longer than 90 minutes athletes should be drinking a fluid that contains carbohydrates or electrolytes so maintain blood glucose. This helps slow the use of muscle glycogen.

Post Exercise Nutrition
The goal at this time is to rehydrate, refuel, and help promote growth. This should be done within an hour of finishing exercise. The best approach is to have a meal rich in carbohydrates, fluids and protein. Recovery drinks such as chocolate milk, skim milk or a recovery drink is also good.

Hydration and fluid Intake
During exercise our bodies generate a lot of heat. If we don’t release this heat our bodies could over heat. In extreme environments where it is very hot it makes it difficult for our bodies to release heat and increasing the risk for heat related injuries. The solution is to drink water

Water Intake and Temperature Regulation
Water distributes heat evenly throughout the body and enables heat to be released from the body through sweat. There are 2 main neurological processes that our bodies use to help cool itself down during exercise and when we are exposed to heat.

Reflex dilation of skin : This is when blood vessels dilate in the skin to force more blood to the surface of the skin. With an increased blood flow heat is transferred to the skins surface and released into the environment. Sweating reflex: This activates the sweat glands in our skin, which release sweat on the skins surface. Then the sweat will evaporate and remove heat from the skin.

Hydration and Rehydration
Before exercise it is good to consume 2-3 cups of water 2-3 hours prior to exercising as well as consuming 1 cup minutes before you start training. Drinking a carbohydrate drink 2-3 hours prior to exercise can help maximize your glycogen stores.

During Exercise For any activity lasting minutes drinking water is recommended. Sport beverages containing carbohydrates might be useful when activity is longer than minutes. The ideal carbohydrate concentration level in a sport drink is 6-8%. Including some salt and other electrolytes will increase thirst making you drink more water as well as replacing electrolytes that have been lost.

6-8% = 6 to 8g/ 100 mL and 0.5g of sodium per litre of fluid is optimal for fluid replacement.
Drink at least one half cup of cool fluid after each 10 minutes of exercise. You shouldn’t consume more than 60g of carbohydrates per hour. More than that could lead to nausea or upset stomach.

After Exercise Rehydration after exercise should take place as soon as possible. Drinks should contain carbohydrates and electrolytes to replace glycogen stores and speed rehydration. Some protein in a recovery beverage is said to help with hydration.

For athletes or active individuals they should try to consume around 150% of the fluid they have lost during exercise. For example if the athlete weighs 100kg before exercising and after weighs in at 98kg the estimated fluid loss is 2kg or 2L. They should try and consume 3L of water in the next 2-3 hours after exercise.

Hyponatremia This is when someone “overdoses” on water. Water toxicity can develop if someone drinks so much water that it dilutes the blood and upsets the bodies normal water balance. This normally happens when novice athletes consume excessive amounts of water during endurance exercise and especially in hot environments where they sweat a lot

This leads to muscle weakness, cramping, nausea and vomiting, head aches, confusion and even unconsciousness and coma. Ways to avoid this problem include: consult a coach or nutritionist about using sports drinks that contain sodium to help with long distance endurance events. Monitor salt intake days leading up to the event. Try not to drink more than you sweat