Energetics, BMR, and Thermoregulation

Energetics

• Energetics studies the flow and conversion of energy in biological systems
• Metabolic rate refers to the overall rate at which metabolic reactions use energy, with some energy being converted to ATP while some is lost as heat
• Basal metabolic rate (BMR) is a standard benchmark for energetics studies, defined as the minimum resting energy expenditure of an awake, alert person

Basal Metabolic Rate

• Basal metabolic rate (BMR) is measured when the body is in a quiet, resting, and fasting condition
• The average BMR is around 70 Calories per hour, totaling about 1680 Calories per day
• BMR can vary based on factors like size, weight, and physical activity level
• Adequate food intake is necessary to support an individual's activities

Thermoregulation and Heat Balance

• Metabolic activities generate heat, with about 40% of energy used to form ATP and 60% released as heat
• Temperature is measured in calories; a calorie is the amount of energy to raise 1 gram of water by 1°C, and a Kilocalorie (kcal) or Calorie (Cal) equals 1000 calories
• Homeostatic mechanisms maintain a normal internal body temperature despite environmental fluctuations
• Core temperature is normally around 37°C (98.6°F), while shell temperature is 1-6°C lower
• Maintaining core temp is important for biological function

Mechanisms of Heat Transfer

• Radiation involves heat energy transfer as infrared radiation, like heat from the sun; about 50% of body heat loss indoors occurs through radiation
• Convection is heat loss due to air movement; warm air rises from the body and is replaced by cooler air; about 15% of body heat loss indoors is attributed to convection
• Evaporation occurs when water changes from liquid to vapor, absorbing 0.58 Cal per gram of water and cooling the skin's surface
• Insensible perspiration continually releases about 20-25 mL of water per hour from alveoli and skin; accounts for about 20% of body heat loss indoors
• Sensible perspiration from sweat glands can excrete 2-4 liters of water per hour
• Conduction uses direct energy transfer through physical contact and is not generally an effective method for gaining or losing heat

Maintaining Core Temperature

• Blood vessels in the dermis constrict to reduce heat loss via radiation and convection when core temp declines
• Contraction of arrector pili reduces heat loss
• Thyroid hormones, epinephrine, & norepinephrine increase cellular metabolism generate heat when core temp declines
• Shivering generates heat
• Dilation of skin blood vessels allows heat loss through radiation and convection when core temp is too high
• Sweat glands stimulate heat loss through evaporation
• Metabolic rate decreases to generate less heat

Appetite Regulation

• Two hypothalamic areas help regulate appetite; one stimulates feeding and the other suppress it
• Appetite regulation is influenced by social factors, psychological pressures, and dietary habits
• Appetite regulation occurs at short-term and long-term levels

Short-Term Appetite Regulation

• Short-term appetite regulation includes stimulation of the satiety center, which increases elevated blood glucose levels
• Hormones of the digestive tract, like CCK, and stretching of the digestive tract wall also can suppress appetite
• Stimulation of the feeding center is triggered by neurotransmitters, such as neuropeptide Y (NPY) from the hypothalamus
• Hormone secretion from the gastric mucosa when the stomach is empty can encourage hunger

Long-Term Appetite Regulation

• Long-term appetite regulation involves stimulating the satiety center which effects leptin
• Leptin is made from peptide that is secreted by adipocytes
• Leptin stimulates the satiety center and suppresses appetite gradually

Metabolic Syndrome

• Metabolic syndrome involves a cluster of conditions that, when occurring together, increase the risk of cardiovascular disease, stroke, and type II diabetes
• Metabolic syndrome is defined by the following criterion: central obesity and 2 of the following: a systolic blood pressure greater than 130 or diastolic pressure greater than 85 mmHg, increasing truglycerides, reduced HDL cholesterol, high fasting blood glucose
• Metabolic syndrome affects an estimated 25% of the adult population worldwide
• Risk factors include lifestyle, poor diet, high BMI, genetics, smoking, socioeconomic status and lack of education

Importance of Nutrition

• Diet is a modifiable risk factor that can influence long-term health prospects more than any other factor
• Sleep and physical activity are also important modifiable risk factors
• Nutrition, in turn can influence Hypertension, cardiovascular disease, cerebrovascular disease, kidney disease, diabetes, obesity and cancer

Nutrition Defined

• Nutrition is the science of how food and drink affect human health
• Nutrients are essential for energy, growth, and bodily functions.
• Non-nutrients do not provide energy but have health benefits
• Fibre aids digestion
• Phytochemicals are compounds in plants that may lower disease risk
• Essential nutrients are acquired from diet
• Essential fatty acids (omega-3 and omega-6)
• Essential amino acids

Macronutrients

• Macronutrients are the nutritive components of food that provide the body with energy
• Macronutrients are also known as macros
• The three macronutrients are carbohydrates, proteins, and lipids

Macronutrients and Proportion

• All three macronutrients (carbohydrates, lipids, protein) are needed for proper health, including fats
• A healthy diet should not exclude or seriously restrict macronutrients
• 45%-65% of calories should come from carbohydrates
• 25%-35% of calories should come from fats
• 10%-35% of calories should come from proteins
• These amounts will shift depending on individual goals

Carbohydrates

• Carbohydrates are a main nutrient that serves as source of energy
• Carbohydrates yield four calories of energy per gram of food and should make up 45-65% of the daily diet
• This macronutrient includes sugars, starches, and fiber
• There are two types of carbohydrates: simple and complex

Simple Carbohydrates

• Simple carbohydrates are sugars that enter the bloodstream rapidly and provide energy quickly
• Simple carbohydrates provide calories but few vitamins and minerals
• Simple carbohydrates are present in milk, fruit and many vegetables

Complex Carbohydrates

• Complex carbohydrates are starches and fibers
• Starch is a substance that is made and stored in plants
• Fiber is apart of grains and plants that cannot be digested
• Complex carbohydrates in foods are legumes, breads, pasta and vegtables

Complex vs Simple Carbohydrates

• Complex carbohydrates nourish the body better than simple carbohydrates
• Complex carbohydrates should make up the bulk of carb intake; simple carbohydrates should be eaten in moderation

Fiber

• Fiber is part of grains and plant foods that cannot be digested
• Soluble fiber is one type of fiber
• Insoluble fiber is the other type of fiber
• Insoluble fiber helps prevent constipation and other intestinal problems by binding with water
• Insoluble Fiber helps reduce colon risk
• Soluble fiber helps lower cholesterol and reduce the risk of heart disease

Lipids

• A lipid provides the body with energy and helps the body store and use vitamins
• Fats provide nine calories of energy per gram of food and should make up 25-35% of the diet
• The body needs fats to maintain body heat, maintain an energy reserve, and build brain cells and nerve tissues
• Saturated fats, unsaturated fats, and trans fats are types of fats

Saturated Fats

• A type of fat found in dairy products, solid vegetable fat, and meat and poultry
• These fats are most often solid at room temperature
• butter, palm and coconut oils, cheese, and red meat have high amounts of saturated fat
• Saturated fats may contribute to the level of LDL cholesterol

Unsaturated Fats

• Liquid at room temperature
• They are considered beneficial fats because they can improve blood cholesterol levels and play a number of other beneficial roles
• Predominantly found in foods from plants, such as vegetable oils, nuts, and seeds
• Monounsaturated fats (MUFAs) and polyunsaturated fats (PUFAs) are the two types
• Monounsaturated fats are found in avocados and canola oils
• Polyunsaturated fats are found in sunflower and flaxseed oils

Essential Unsaturated Fats

• Omega-3 fats are an type of essential polyunsaturated fat
• Consuming fish is a way to get omega-3 fats 2-3 times a week
• Flax seeds, walnuts, and canola or soybean oil are excellent sources

Trans Fats

• Created by hydrogenating vegetable oils, makes them more stable and less likely to become rancid, and converts the oil into a solid
• Partially hydrogenated oils can withstand repeated heating without breaking down, making them ideal for frying fast foods
• Partially hydrogenated oils became a mainstay in restaurants for frying, baked goods
• Trans fats are also naturally found in beef fat and dairy fat in small amounts

Trans Fats and Limiting

• Trans fats are associated with heart and blood vessel issues
• Raise bad LDL and lower good HDL
• Contribute to insulin resistance
• Consumption should be limited to less than 1% of daily calories
• < 2.2 g maximum

Choosing Lipids

• One doesn't eat the correct intake of unsaturated fats
• the American Heart Association suggests 8-10% of daily calories should come from polyunsaturated fats
• Evidence suggests that eating more polyunsaturated fat (up to 15 percent of daily calories) in place of saturated fat can lower heart disease risk.
• Saturated fats should make up less than 10% of daily calories.
• Trans fats should be limited to less than 1% of daily calories.

Proteins

• Needed for growth and the building and repairing body tissues
• Proteins are needed to regulate body processes and to supply energy
• Proteins supply four calories of energy per gram of food and should make up 10-30% of your diet
• There are two different kinds of proteins
• complete proteins
• incomplete proteins
• Building blocks that make up proteins are amino acids
• Human bodies need 20 amino acids to function properly
• Humans create 11 amino acids
• Those that are not created are essential amino acids

Complete Protein

• The proteins contain that all the essential amino acids
• Examples are meat, eggs, and fish
• vegetarian examples: Quinoa, soybean, and buckwheat

Food Combining

• Combining foods such as grains and nuts is a good approach
• Eating a well balanced diet over all is a great way to get amino acids

Meeting Demands

• Plant foods such as legumes, lentils, nuts, seeds and whole grains on a daily basis are important
• There are rarely cases of protein deficiency
• A vegetarian is adequate enough

Micronutrients

• Nutrients needed by the body in small amounts
• Vitamins, minerals, and trace minerals
• Needed for maintaining health and preventing disease
• Do not provide energy

Vitamins

• Organic compounds present in small quantities in different types of food
• They help in various biochemical processes in the cell
• Important for growth and good health
• Essentail
• non-Caloric
• Required in very small amounts

Vitamins Listing

• Fat-Soluble Vitamins
  • A, D, E, and K (stored in the body)
• Water-Soluble Vitamins
  • Ascorbic acid (vitamin C)
  • Thiamin (vitamin B1)
  • Riboflavin (vitamin B2)
  • Niacin (vitamin B3)
  • Pyridoxine (vitamin B6)
  • Biotin (vitamin B7)
  • Pantothenic acid (vitamin B5)
  • Folate (vitamin B9)
  • Cobalamin (vitamin B12)

Vitamin Functions

• Vitamins act as hormones
• Vitamins act as antioxidants
• Act as mediators of cell signa;ling and regulators of cell and tissue growth and in blood clotting
• Act as precursors for coenzymes

Minerals and Trace Elements

• Macrominerals (>100 mg/day)
  • Calcium, Phosphorous, Sodium, Potassium, Chloride, Magnesium
• Microminerals (<100 mg/day)
  • Iron, lodine, Copper, Manganese, Zinc, Cobalt, Molybdenum, Selenium, Fluoride, Chromium, Silicon

Function of Elements

• Elements act as cofactors, electrolytes, and structural roles Part of the hormones and transport
• Conduct signals

Minerals and Toxicity

• RDAs/Als ensure the prevention of disease
• RDA = Recommended Dietary Allowance
• AI = Adequate Intake
• Deficienies are not a big problem in Canada
• Toxicities can have a larger effect on those who are highly sensitive

Deficiencies

• Vitamin D is the most common nutrient deficiency in Canada
• Followed by Iron, Magnesium, Iodined, and Vitamin A

Canada's Food Guide (2019+)

• Focuses on whole grains, fruits, vegetables, and protein from plants
• Water is a choice drink
• Portion the 3 ingredients to specific intake

Pros of CFG

• Science based and has straightforward recommendations
• Focuses on whole foods over processes
• Promotes healthy eatting habits (cooking, community)
• Website listed has fantastic information (https://food-guide.canada.ca)
• Promotes a non-diet approach

Cons of CFG

• Not applicable for many populations
• Not a lot of budget friendly options
• Doesn't account for cultural pops and vulnerable people