Weight Management: Nutrition & Physical Activity

1. Weight Management: Nutrition & Physical Activity Chapters 7 & 13

2. Influences on Hunger • Hunger • Physiological response to nerve signals and chemical messengers • Hypothalamus: control center in brain • Many influences! • Volume or pressure of food in GI tract • Presence of nutrients in blood, release of hormones in response • Nutrients’ influence on neurotransmitters, which in turn influence hunger • Liver metabolism, which is influenced by nutrients • Absence of hunger • Satiation – signal to stop eating • Satiety – satisfaction between meals; signal not to eat • We can override hunger/satiety signals • Appetite • Distraction • Social pressure • Emotions • Stress

3. Energy In: Food Composition

4. Sustaining Satiation and Satiety • Nutrient composition • Protein is most satiating • Low-energy density, high-fiber foods tend to be more satiating • Why? • High-fat foods – strong satiety signals • Why? • Balance among protein, fat, carbohydrate and fiber at each meal & snack is the goal

5. Energy Out • We utilize energy from food for moving body, fueling chemical reactions, functioning of organs • These functions generate heat • Thermogenesis • Basal metabolism • Physical activity • Food consumption: digestion & absorption • Adaptation

6. Components of Energy Expenditure – Basal Metabolism • About two-thirds of energy expended in a day • Metabolic activities • All basic processes of life • Basal metabolic rate (BMR) • Varies greatly from one individual to the next! • Major influence that we can control: amount of lean tissue

7. Components of Energy Expenditure – Basal Metabolism

8. Components of Energy Expenditure – Physical Activity • Voluntary movement of skeletal muscles • Most variable component of energy expenditure • Amount of energy needed • Muscle mass • Body weight • Activity • Amount expended depends on frequency, intensity, and duration of activity

9. Components of Energy Expenditure – Thermic Effect of Food • Digestion, absorption, and utilization on nutrients costs energy and releases heat • Acceleration of GI tract functioning in response to food presence • Oxidation or other use in body • Accounts for approximately 10% of energy intake • Energy cost depends on macronutrient • Lowest to highest: Fat, CHO, Protein • Diet high in fat vs. carbohydrate?

10. Components of Energy Expenditure – Adaptive Thermogenesis • Adapt to dramatically changing circumstances • Examples: intense physical conditioning, extreme cold, trauma, stress • Extra work done by body • Amount expended is extremely variable • Not included in energy requirement calculations

11. Fat Cell Metabolism • Lipoprotein lipase (LPL) activity • Storage of triglycerides • Obese people vs. lean people • Activity in varying body regions • Men vs. women • Enzyme activity releasing and breaking down fat: individual differences • LPL activity increases after weight loss

12. Causes of Overweight & Obesity – Genetics & Epigenetics • Causative role of genetics? • Genetic influences do seem to be involved • Genetics may determine predisposition to obesity • Epigenetics • Gene expression influenced by: • Diet • Physical activity • Satiety and energy balance

13. Causes of Overweight & Obesity – Environment • Encountered daily circumstances • Interaction between environment and genetics (epigenetics) • Overeating • Present and past eating and activity patterns influence current body weight • Availability • Serving sizes • Restaurant food

14. Problems of Overweight and Obesity – Perceptions & Prejudices • Most obese people do not successfully lose weight and maintain the loss • Social consequences • Jobs, school, and in social situations • Psychological problems • Embarrassment • Other feelings

15. Problems of Overweight and Obesity – Perceptions & Prejudices

16. Weight Cycling

17. Why is it hard to lose weight? • When energy intake is low, the body conserves energy and resists weight loss • Metabolism slows • Hunger hormones, such as ghrelin, increase • Satiety hormones, such as leptin, decrease • LPL activity increases • Those who use diet alone as a weight loss strategy are not usually successful in the long term

18. Crash Diets and Weight Loss Fads • Diet books and weight-loss programs • Little success with weight loss maintenance • Weight-loss products • Shakes, pills • Herbal products • Laws for dietary supplements • Other gimmicks • Body wraps, saunas, cellulite creams

19. Problems with Excessive Restriction • Not sustainable • Wastes lean body mass • Diminishing returns • Inadequate intake of nutrients hampers metabolism • Extremely difficult to meet needs below 1200 kcals • Very-low-calorie diets can have serious health consequences • Gallstones • Fatigue • Nausea • Cold intolerance • Light-headedness • Nervousness • Constipation or diarrhea • Anemia • Hair loss • Dry skin • Menstrual irregularities

20. Other Dietary Strategies • Low-fat • Reduced satiety • Tend to be high in carbohydrate • Potential blood sugar peaks and valleys • Increased insulin release • Promotes storage • Low-fat does not equal low-calorie • Low-carbohydrate • Protein is satiating • Ketone body production reduces hunger • Food choices limited (monotony leads to less eating) • Long-term effects still unclear Bottom line: either approach may result in weight loss, but only if overall energy intake is less than expenditure. The ability to stay with the dietary approach generally predicts long-term success.

21. Weight Loss Strategies • Successful strategies • Small changes toward patterns of eating and exercise that you could reasonably sustain for life • Moderate losses • Significant improvement in health outcomes with loss of 5-15% of body weight • Reasonable goals • Reasonable rate of weight loss: 0.5 to 2 pounds per week • Incorporation of healthy eating and physical activity

22. Weight Loss Strategies – Eating Plans • Be realistic about energy intake • Create an energy deficit, but • Avoid restrictive eating • Avoid rapid weight loss – it’s not just fat you’re losing! • Goal: nutritional adequacy without excess • Deficit of 500 to 1000 kcalories per day • Greatly assisted by physical activity!! • Breakfast frequency • Inversely related to obesity!

23. Weight Loss Strategies – Eating Plans • Nutritional adequacy • Minimum of 1200-1500 kcalories a day • Eat small portions of energy-dense food • Eat less calorie-dense food at each meal • Feel satisfied, not stuffed: Hara hachi bu • Load up on foods of lower energy density • Veggies, fruits, and lean proteins! • High-fiber foods: • Low in energy and high in nutrients • Require effort to eat • Speed of food consumption • Price of food vs. health cost

24. Weight Loss Strategies – Eating Plans • Remember water • Assistance with weight management • To fat or not to fat? • Energy density vs. satiety • See study! • Watch for empty kcalories • Fat, sugar, and alcohol • Select carbohydrates carefully • Whole vs. refined • Quality and quantity matter • Artificial sweeteners • Impact on energy intake

26. Importance of Physical Activity • Best approach to weight management • Moderate physical activity plus activities of daily life • Combination of diet and physical activity • Lose more fat • Retain more muscle • Regain less weight • Reduction of abdominal fat • Especially resistance and HIIT • Cortisol connection

27. Weight Loss Strategies – Physical Activity

28. Physical Activity • Body composition • Fat decreases and lean body mass increases • Decreased abdominal fat, decreased disease risk • Appetite control • Delayed appetite • Reduces eating in absence of hunger • Reduces emotional/stress eating (since it helps to manage stress) • Another cortisol connection!

29. Weight Maintenance • Successful weight loss • Plateau • Appropriate goal at this point? • Changing up physical activities • Sustained weight loss • Takes more effort to preventregain than to prevent initial gain • Increased lean body mass helps

30. Underweight • Affects no more than 5% of U.S. adults • Weight gain is a matter of health • Individual matter • Weight gain may be difficult • Demand for energy contributes to underweight • Physical activity • Growth and development

31. Weight-Gain Strategies • Key diet planning strategies • Adequacy and balance • Energy-dense foods • Regular meals daily • Large portions • Extra snacks • Liquid meals (shakes)

32. Fitness • Depends on physical activity and exercise (not body type!) • Regular physical activity • Increased strength and flexibility and ability to perform daily activities • Additional benefits include • Weight management • Cardiovascular health • Diabetes prevention or management • Bone and joint health • Possible reduction of cancer risk • Psychological health

33. More Benefits of Fitness • Restful sleep • Optimal body composition • Resistance to infectious diseases • Lower incidence of anxiety & depression • Lower risk for some types of cancer • Strong circulation & lung function • Stress reduction • Cortisol reduction • Strong self image • Lower risk of dementia

34. How much should I do? • Highly individual • Just 15-20 min/day starts to reduce disease risk • Minimum for optimal health: 2.5 hrs moderate or 1.25 hrs vigorous activity • Not an upper limit! • Greater benefits can be seen by increasing duration or intensity • Good to spread out over the week • Excessive sedentary activity can decrease benefits and increase CVD, depression, waist circumference, and other adverse effects

36. Developing Fitness • Minimizing risk of overuse injuries • Be active all week • Use proper equipment and attire • Use proper form • Include warm-up and cool-down activities • Challenge your strength and endurance a few times a week • Mix it up! • Pay attention to body signals

37. Developing Fitness • Muscle conditioning • Fit muscles use oxygen efficiently • Increased mitochondria and vasculature • Reduces heart’s workload • Burns fat longer • Balanced fitness program • Activities you enjoy doing • Addresses all aspects of fitness • Strength, endurance, flexibility • Each has specific benefits

38. Resistance Training • Purpose • Build muscle mass • Increases metabolism! • Develop and maintain muscle strength, muscle power, and muscle endurance • Benefits for prevention of chronic diseases • Maximizes and maintains bone mass • Improves posture & reduces risk of back injury

39. Nutrition & Physical Performance • Performance and recovery both enhanced by optimal nutrition • We need all essential nutrients to power movement • 3 energy systems: • ATP-CP, anaerobic, and aerobic • All 3 systems always active and work together • ATP-CP (creatine phosphate) • Stores of ATP and CP only power muscles 3-15 seconds • Muscle and liver glycogen needed to continue contraction

40. Fueling Exercise by the Minute

41. Creatine Phosphate • Popular supplement (ergogenic aid) • Studies show improvement in muscle strength and power • No benefit for aerobic training • Possible side effects: • Weight gain (water retention) • GI symptoms: nausea, diarrhea, abdominal pain • Rash, anxiety, headache, fatigue • Not appropriate for people with kidney issues • Should be avoided in children, adolescents, pregnant women, nursing mothers, diabetics

42. Anaerobic vs. Aerobic • Anaerobic activities and fatigue • High-intensity; outstrips body’s ability to deliver oxygen • Anaerobic glycolysis leads to drop in pH • Impairs glycolysis, inhibits binding of calcium in muscle • Aerobic activities and endurance • Lower-intensity, requires oxygen • Oxidative metabolism of energy nutrients • Produces much more ATP, but at slower rate • Uses glucose and fatty acids

43. Endurance • As long as ATP supply meets energy needs, activity can continue • Rate/intensity of activity influences energy system used • Anaerobic exercise: CP and glycogen rapidly depleted • Level of training highly influences shift to anaerobic metabolism • Number of mitochondria and efficiency of oxygen delivery increase with training

44. Glucose Use During PA • Exertion • Liver breaks down glycogen • Release glucose into bloodstream • Muscles use glucose and stored glycogen • Muscle fatigue when glycogen is depleted • Glycogen storage: limited • Intensity of activity • Impacts how long glycogen will last • CHO post-workout restores glycogen, spares muscle tissue

45. Protein Use & PA • Not a significant part of fuel mix for most • Used in muscle building • Synthesis suppressed during activity; accelerates afterward • High-quality protein consumption • Enhances muscle protein synthesis • What is a high-quality protein? • Protein needs are higher for endurance and strength athletes • Need adequate CHO, as well…why?

46. Recommended Protein Intakes for Athletes • Endurance athlete: 1.2-1.4 g/kg body weight • Strength athlete: 1.6-1.7 g/kg body weight • Everyday adults: minimum of 0.8 g/kg body weight • Max. usable amount for adults: 2.0 g/kg body weight • Risks of excessive protein intake • Dehydration • Mineral losses

47. Vitamins and Minerals to Support Activity • Roles in supporting activity • Assist in releasing energy from fuels • Transport of oxygen • Multiple vitamins and minerals, as well as protein, involved! • Supplements • Vast majority do not enhance performance of well-nourished people

48. Fluids and Electrolytes to Support Activity • Fluid replacement via hydration • Hydrate before activity • Drink extra fluid in the days before event • Rehydrate during and after activity • Fluids for everyday, active people • Plain, cool water • Fluids for endurance athletes • May benefit from mineral and CHO-containing beverages

49. Sports Drinks vs. Water • Sports drinks • Hydration is critical to optimal performance • Water is best for most people • Sport drinks offer the following • Fluid • Glucose • Sodium and other electrolytes • Some prefer the flavor

50. Dietary Strategies for Active People • Hydrate • Thirst is a late signal of need • Choose nutrient-dense foods • Vitamins & minerals • Consume adequate energy • Need all energy-yielding nutrients • CHO, protein, and fat • Meal frequency and balance • Stable blood glucose means stable energy levels • Optimal maintenance of lean tissues