Chapter 9 - Specifically, Interpreting Body Weight + Other Random Info

Proximate composition calculation.

19 grams of protein in 3oz salmon fillet 5 grams of carbs in 1 cup of chopped broccoli 37 grams of fat in 1 cup of shredded cheddar cheese 9kcal/1 gram of fat 4kcal/1 gram of carbs or protein Kcal of protein = 76 Kcal of carbs = 20 Kcal of fat = 333 Total kcal = 429

Methods used to determine the energy a food contains.

A bomb calorimeter. This instrument is designed to burn a food while measuring the amount of heat or energy released. Proximate composition determines the grams of carbohydrates, proteins, and fats of a food item. The grams are then multiplied by the energy value of each (carbohydrates 4 kcal/g; proteins 4 kcal/g; fats 9 kcal/g). The sum of these calculations equals the total energy content of a specific food.

Energy released from food measured in kcals (or thousands of calories).

A calorie is the amount of heat necessary to raise the temperature of a gram of water by 1° C (0.8° F).

Body fat and calories.

A pound of body fat is roughly equivalent to 3500 kcal.

Factors affecting BMR.

Age, body size, sex, body temperature, fasting/starvation, stress, menstruation, and thyroid function.

Interpreting weight using body mass index (BMI).

BMI is calculated by dividing the weight in kilo-grams by the square of the height in meters. Body Mass Index (BMI) = (weight (kg) / height (m2) Example: Your weight = 68 kg / Your height = 1.65 m (165 cm) BMI Calculation: 68 ÷ 1.652 = 24.98. 1 inch = 0.0254 meters 12 inches = 1 foot 1 kg = 2.2lbs.

Athletes and carbs.

Carb consumption depends on body size of the athlete and the intensity/level of training. Athletes participating in high-energy sports that require short bursts of energy (e.g., basketball, tennis, foot-ball, soccer) need about 5 g of carbohydrate per kilogram of body weight daily. 150lb athlete = 68kg x 5 = 340g of carbs/day Endurance athletes who train aerobically for more than 90 minutes daily may need a higher intake of carbohydrate per kilogram of body weight to replace glycogen.

Hyponatremia

Deficient sodium in the blood which can because caused by excessive fluid intake. May occur in athletes.

Physical activity.

Demands about 20% to 30% of our total energy needs. A heavier person uses more energy to perform a given task than a lighter person.

Adipocytes

Fat storing cells (in the form of triglycerides). Most of the fat in our bodies is stored in adipocytes.

Visceral fat

Fat that is visceral in the abdominal cavity seems to be much more dangerous than subcutaneous such as lower body fat or the fat under the skin in the abdominal area. Visceral fat is more easily lost and also more quickly regained than subcutaneous abdominal fat or lower body fat.

Athletes and fat needs.

Intake of 20% to 25% energy from fat

Gender-based essential fat percentages.

Men (essential) - 3% t0 8% of body weight Total fat, within healthy range - 15% to 20% Women (essential) - !2% to 14% Total fat, within health range - 25% to 35% (takes into consideration childbearing and lactation = more fat)

Assessing fat distribution patterns using waist to hip circumference.

Men (healthy ratio) - less than 0.95 to 1 Women (healthy ratio) - 0.8 or less People with waist measurements more than 40 inches (102 cm) for men and more than 35 inches (88 cm) for women are at greater risk for the various chronic diseases associated with obesity.

Adipocyte hyperplasia

Occurs during the growth spurts that accompany normal development - infancy, the preschool years, adolescence, and pregnancy.

Adipocyte hypertrophy

Occurs whenever we continue in positive energy balance for any time. Contributes to obesity. Causes can include genetics, diet, overeating, sedentary lifestyle. If more energy is consumed than expended, fat storage will go on until the fat droplet reaches its maximum size. If the positive energy balance continues, the body will make new adipocytes, thereby expanding the storage capacity.

The Dietary Reference Intake (DRI) for protein for sedentary adults and athletes.

Sedentary adults is 0.8 g per kilogram of body weight per day. Athletes need between 1.5 and 2 g of protein per kilogram of body weight per day.

The energy source that muscles use during exercise.

Short-term, high-intensity activities such as sprinting rely mostly on the anaerobic pathway for energy, and only carbohydrates (primarily from muscle glycogen). Exercise of low to moderate intensity is supported primarily by the aerobic system, and both carbo-hydrates and fats are used. A sedentary person breaks down glycogen faster and as a result accumulates more lactic acid in the tissues. The lactic acid causes muscle fatigue. Endurance training increases the capacity of the muscles to store glycogen.

Genetic influences related to obesity.

The endocrine influence of the hormones leptin and ghrelin. Leptin inhibits food intake and regulates long-term appetite. Ghrelin increases appetite and/or food intake. Mutations in functions of leptin and leptin receptors may have a role in the development of obesity. Ghrelin, which circulates in plasma, makes up part of the adaptive response of the body to weight loss by leading the body to regain lost weight.

Resting energy expenditure (REE)

The energy a person expends in a normal life situation while at rest, and it includes some energy the body uses following meals and exercise. Accounts for approximately 60% to 75% of our total energy needs.

Thermic effect of food (TEF)

The energy required for our body to digest, absorb, metabolize, and store food. Accounts for approximately 7% to 10% of a person's total energy needs.

Adaptive thermogenesis

The energy used by our bodies to adjust to changing physical and biologic environmental situations. This includes energy used to adapt to coldness, extreme changes in kcal intake (of several days' duration), and physical and emotional trauma.

Athletes and nutritional needs.

The nutritional needs of athletes are basically no different from those of nonathletes, with the exception of kcal and fluids. A diet that provides a variety of foods supplying 45% to 65% of kcal intake from carbohydrate, 20% to 35% of kcal intake from fat, and 10% to 35% of kcal intake from protein is recommended for health and performance. However, some forms of heavy training increase the requirement for certain nutrients. For example, carbohydrates are an important source of energy during endurance exercise, and therefore runners, cyclists, and swimmers may need more carbohydrates (60% to 70% of their total kcal intake) than other individuals. Body size affects kcal requirements more than any other single factor. The smaller the athlete, the lower the kcal requirement. Ideally, kcal intake should balance energy expended. Sweat loss of 1 pound (2.2 kg) of body weight is equal to 2 cups (480 mL) of water. For every pound lost, an athlete needs to drink 2 cups of fluid. To hydrate the total body, the fluid needs to leave the stomach quickly to be distributed throughout the body. Although larger volumes of fluid empty more rapidly from the stomach, many athletes cannot exercise with a full stomach. Cool fluids empty faster from the stomach than warm fluids.

Set point

The point at which an individual's "weight thermostat" is supposedly set. When the body falls below this weight, an increase in hunger and a lowered metabolic rate may act to restore the lost weight. Adjustments our bodies make to return to the set point are called defending the set point. Weight loss may cause constant hunger if the body falls below its set point.

Carbohydrate loading.

To achieve maximum muscle glycogen stores through carbohydrate loading, athletes should consume a high-carbohydrate diet as part of their regular training program. At least 60% (preferably 60% to 70%) of their total kcal should come from carbohydrate. For the athlete eating 3000 kcal a day, this proportion represents a minimum of 450 g of carbohydrate daily.

BMI ranges.

Underweight: less than 18.5 Normal: 18.5 to 24.9 Overweight: 25 to 29.9 Obese: greater than 30

BMI example using my weight/height.

Weight = 141 lbs. Height = 5'4 141/2.2 = 64 kg 5'4 = 64 inches 64 in x 0.0254m = 1.626m 1 in 64 x 1.626^2 = 24.2