Dietary Fats: Types and Effects

Types of Dietary Fats

• Dietary fats are classified as healthy or unhealthy

Healthy Fats: Monounsaturated Fats (MUFA)

• MUFAs help lower total and LDL ("bad") cholesterol
• These fats maintain or boost HDL ("good") cholesterol levels
• They may also aid in lowering blood pressure
• MUFAs are liquid at room temperature
• MUFAs contain one double bond in their structure
• Food sources include avocados, olive oil, peanut oil, nuts, and seeds
• MUFAs are rich in phytonutrients and antioxidants, especially extra virgin olive oil
• They are linked to a reduced risk of heart disease

Healthy Fats: Polyunsaturated Fats (PUFA)

• Omega-3 fatty acids reduce inflammation, support heart rhythm, and lower triglyceride levels
• Omega-6 fatty acids are important but require balance with omega-3s

Function and Effects of PUFAs

• PUFAs lower LDL cholesterol and reduce total cholesterol levels
• They are liquid at room temperature

Food Sources of PUFAs

• Omega-3 sources include fatty fish (salmon, mackerel, sardines), flaxseeds, and walnuts
• Omega-6 sources include vegetable oils (corn, safflower, soybean)

Supplement Considerations for PUFAs

• Fish oil supplements can be helpful but may carry risks like mercury contamination and bleeding at high doses

Unhealthy Fats: Saturated Fats

• Saturated fats increase LDL cholesterol levels

Sources of Saturated Fats

• Saturated fats come from animal products like butter, cheese, and red meat
• Tropical oils like coconut oil and palm oil are also sources of saturated fats

Unhealthy Fats: Trans Fats

• Trans fats increase LDL and decrease HDL cholesterol
• Sources include processed foods, baked goods, and products with partially hydrogenated oils

Dietary Cholesterol

• Dietary cholesterol has a minor effect on blood cholesterol for most individuals
• It is found only in animal-derived foods like egg yolks, meat, and full-fat dairy

Dietary Recommendations and Calculations

• Protein foods include fatty meats, poultry skin, fried meats, eggs, nuts, seeds, peanut butter, and fatty fish
• Dairy includes whole milk, cheese, butter, cream, and ice cream
• Grains include baked goods, granola, and crackers
• Vegetables include fried vegetables and creamy sauces
• Fruits are very low in fat naturally which can be added through cream or frying
• Oils include vegetable oils, margarine, butter, shortening, mayonnaise, olive oil, and avocado oil.

Ways to Cut Fat in the Diet

• Eat more lean meats (skinless poultry, lean beef), low-fat or fat-free dairy, grilled/baked/steamed foods, fruits, vegetables, whole grains, and fatty fish (salmon, tuna)

• Eat less fried foods and processed meats (bacon, sausage), full-fat dairy, baked goods with butter/lard, and foods with trans fats

Fat Recommendations

• Total fat intake should be 20–35% of total calories
• Saturated fat should be less than 10% of total calories
• Trans fat intake should be as low as possible
• Cholesterol intake should stay under 300 mg/day
• EPA/DHA (Omega-3) intake should be 250–500 mg/day

Fat Intake Calculations

• For example, in a 2000 calorie diet, 30% of calories from fat is 600 kcal (30% of 2000)
• This equates to approximately 67 grams of fat per day (600 ÷ 9)
• It is important to know daily limits for total fat, saturated fat, trans fat, and cholesterol based on calorie needs

Essential vs. Non-Essential Amino Acids

• Essential Amino Acids (EAAs) cannot be made by the body in sufficient amounts and must be obtained from the diet
• Non-Essential Amino Acids can be synthesized by the body and are not required through diet
• There are 20 total amino acids; 9 of them are essential

Essential Amino Acids

• The 9 essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine

Role of Protein in Food

• Protein is needed for growth and repair of tissues
• It is needed for enzyme and hormone production, immune function, and transporting nutrients
• Protein provides energy: 4 calories per gram

Excess Protein/Amino Acids

• Excess amino acids are deaminated, and the nitrogen is excreted as urea
• The remaining carbon skeleton is used for energy or converted to fat
• Excess protein intake alone does not build more muscle without exercise

Protein Sparing

• When the body gets enough carbohydrates and fats for energy, it can spare protein for its main roles like tissue building
• If carbs and fats are insufficient, protein is used for energy instead

Protein Quality: Complete vs. Incomplete Proteins

• Complete proteins contain all 9 essential amino acids. Found in animal products (meat, eggs, dairy) and a few plant sources like soy and quinoa
• Incomplete proteins are missing one or more essential amino acids. Found in most plant-based foods (grains, beans, nuts, vegetables)

Complementary Proteins

• Combining two or more incomplete protein sources to form a complete protein
• Examples: rice and beans, peanut butter and whole grain bread, hummus and pita, lentils and tortillas

Calculating Recommended Protein Intake

• The RDA for adults is 0.8 grams of protein per kilogram of body weight
• Formula: Weight in pounds ÷ 2.2 = weight in kg.
• Multiply kg by 0.8 to get daily protein in grams
• Example: 150 lbs ÷ 2.2 = 68.2 kg, 68.2 × 0.8 = 54.6 g protein/day

% of Calorie Method

• Recommended: 10–35% of total calories from protein
• Protein provides 4 calories/gram
• Example: 2000-calorie diet × 0.15 (15%) = 300 protein calories, 300 ÷ 4 = 75 g protein/day

Where Protein is Found (MyPlate)

• Protein Group: Meat, poultry, fish, eggs, nuts, seeds, soy, legumes
• Dairy Group: Milk, yogurt, cheese (complete proteins)
• Grains: Contain some protein, especially whole grains
• Vegetables: Beans, peas, lentils (good plant protein sources)
• Fruits: Very little protein

Protein Content of Common Foods

• 1 cup milk, buttermilk, or yogurt (low-fat or fat-free): 8 grams of protein
• 1 oz regular cheese (cheddar or Swiss; low-fat): 8 grams of protein
• ¼ cup cottage cheese (low-fat or fat-free): 8 grams of protein
• 1 oz meat, poultry, or fish (choose lean meats): 7 grams of protein
• ½ cup legumes (navy, pinto, black beans, lentils, soybeans, peas): 7 grams of protein
• 1 egg: 7 grams of protein
• ½ cup tofu (soybean curd): 7 grams of protein
• 2 tablespoons peanut butter: 7 grams of protein
• 1 to 2 oz nuts or seeds: 7 grams of protein

Protein and Food Labels

• Check grams of protein per serving on the Nutrition Facts label to know how much protein you're getting
• % Daily Value (%DV) is based on 50g/day which is a general guideline and not personalized; example: 10g protein = 20% DV
• Look at the ingredient list for protein sources such as soy protein, whey, casein, egg whites, pea protein
• Protein quality is not shown on the label so you won't know if it's complete or incomplete
• Use labels to compare products and meet your protein goals

Energy Balance

• Energy Balance occurs when the number of calories consumed from food and beverages equals the number of calories the body uses for basic functions, activity, and digestion
• Positive Energy Balance means Calories In › Calories Out leading to Weight Gain
• Negative Energy Balance means Calories In < Calories Out which leads to Weight Loss

Calorie Rule

• A deficit or surplus of 3500 calories is approximately equal to 1 pound of body weight
• To lose 1 pound per week, a person needs a 500 kcal/day deficit; (500 x 7 = 3500)

Basal Metabolic Rate (BMR)

• The number of calories the body needs to maintain basic physiological functions at rest
• BMR makes up the largest portion (60–75%) of total energy expenditure
• BMR is influenced by age, gender, body composition, and genetics

Physical Activity

• Energy used during exercise and non-exercise movements like walking and chores
• Physical activity accounts for about 15–35% of total energy expenditure and varies greatly depending on activity level

Thermic Effect of Food (TEF) / Thermogenesis

• The energy the body uses to digest, absorb, and metabolize food
• TEF constitutes 5–10% of total daily energy use
• The thermic effect of protein is the highest, followed by carbs, then fat.

Body Mass Index (BMI)

• BMI = weight (kg) ÷ height² (m²)
• Used to estimate body fatness and screen for weight categories
• Underweight: <18.5
• Normal: 18.5-24.9
• Overweight: 25-29.9
• Obese: 30 and above
• It does not differentiate between muscle and fat mass