Causes of Obesity and Weight Management Strategies - NFSC100 PDF

Causes of Obesity and Strategies for Weight Management NFSC100 – Elements of Nutrition Margaret Slavin, PhD, RDN University of Maryland, College Park  Agenda ► Causes of obesity ► Lifestyle Strategies for Weight Management Dietary Physical Ac...

Causes of Obesity and Strategies for Weight Management NFSC100 – Elements of Nutrition Margaret Slavin, PhD, RDN University of Maryland, College Park  Agenda ► Causes of obesity ► Lifestyle Strategies for Weight Management Dietary Physical Activity Behavior Modification ► Safe and realistic weight loss ► Available Strategies when Lifestyle Strategies are not enough CAUSES AND PHYSIOLOGY OF OBESITY 3  Inside-the-Body theories of Obesity Genetics, epigenetics, and Obesity – Epigenetics: how environment and behaviors affect gene function. – Our genes haven’t changed, but epigenetics might influence tendency to gain weight or stay lean. Gut microbiome and Dysbiosis Maintenance of normal gut flora Dysbiosis can cause obesity Thermogenesis and BAT Human fat: White adipose tissue - energy storage Image result for brite cells Brown adipose tissue (BAT) energy storage and maintenance of body temperature Heat generating tissue May play a role in keeping people lean Outside-the-Body theories of Obesity External cues to overeating - Available foods, Larger portions, Food supply - Addictive? (Dopamine?) - Unhealthy food Physical inactivity - Screen time - Sedentary jobs Neighborhoods - Built environment - Food deserts THEORIES: CAUSES OF OBESITY Most studies show it’s a combination of many factors. Mainly: Overeating (for many different reasons, including both inside-the-body and outside-the-body reasons) + physical inactivity 6 Hunger, Appetite, Satiation and Satiety  Why Do You Eat? (Hunger) Hunger - Physiological drive to eat - Controlled by internal body (chemical messenger) - Ghrelin: stomach hormone  Targets the hypothalamus  Increases energy intake  Opposes weight loss  Promotes sleep  Why Do You Eat? (Appetite) Appetite - Psychological (external) drive to eat - Can occur without hunger - Factors affecting appetite: – Seeing, smelling – Habit / routine Why Do You Stop Eating? (Satiation/Satiety) Physiological “stop” signals Satiation: Determine the amount of food at one sitting Satiety: lingers in the hours after a meal Regulates frequency of meals – Leptin: Adipokine hormone released from adipose Targets the hypothalamus Reduces food intake & increase energy expenditure Opposes weight gain.  Image result for stomach Gut-Fat-Brain axis in health and obesity Food intake Food Hunger intake Satiety When a person overeats (Feasting)  Energy stores in the body The body stores energy as - Glycogen (liver/muscle) - Triglyceride (fat tissues) - Protein (muscle/organs) Advantage of fat tissue as energy storage source - High energy density - No limit in volume  Adipose tissue and Energy stores Liver triglycerides = 450 kcal Muscle triglycerides = Liver glycogen = 400 kcal 3000 kcal Muscle glycogen = 2500 kcal Adipose tissue triglycerides = 120,000 kcal Data for a 70 kg lean subject. Subject with morbid obesity : x 8 TG (960,000 kcal)  When a person draws on stores (Fasting) If the fast continues beyond glycogen depletion WEIGHT MANAGEMENT Weight Management Strategies ►Lifestyle: Dietary strategies Physical activity Behavior Modification When lifestyle strategies aren’t enough, medical treatment of obesity options exist: ►Drugs ►Bariatric surgery Energy Balance  Realistic Dietary Strategies for Weight Maintenance or Loss ► Manage portion sizes. Read labels. Measure portion sizes ► Eat low energy-density foods. (Lot of volume and nutrients with fewer calories) ► Avoid empty calories. ► Follow an evidence-based food guide (i.e., MyPlate)  Realistic Dietary Strategies ►Ways to feel full without adding calories: Drink lots of water. Choose high-fiber foods. Choose fats and carbs sensibly. Space meals and snacks every few hours, to avoid getting overly hungry. ►Keep a food record! (You already know how!)  Avoid Fad Diets How to spot a fat diet: Claim you can lose weight “easily” or quickly Fast weight loss? If it happens, it’s often it’s due to losing water or muscle! Not fat! Have rigid rules Promote “detoxing” Promote the sale of a product Often inadequate in nutrients A short-term change, not a sustainable lifestyle Lacks scientific evidence 21  Physical Activity ►Regular physical activity is associated with healthier weights and leaner bodies. Burns calories directly. Builds/maintains lean tissue (especially strength training)  Increases metabolism. Exercise helps to normalize appetite.  Enhances feelings of satiation.  Helps manage stress  Physical Activity ►Which type of activity is best? ANY exercise is better than none! Combination  Aerobic  Strength-training Influence of Physical Activity on Discretionary Calorie Allowance  Behavior Modification ► Habits drive behaviors. ► To modify your behaviors, you must first recognize your habits and eating cues. Then, make conscious decisions to: Eliminate inappropriate eating/activity cues. Suppress or strategize around cues that cannot be eliminated. Strengthen cues to appropriate eating/activity. Intentionally repeat desired eating/activity behaviors.  Behavior Modification ►Keeping a diary helps you recognize your behaviors and gives an opportunity to intervene.  Safe Lifestyle Weight Loss ►½ to 2 pounds per week No more than 2 pounds/week. ►About 10% body weight / 6 months ► One pound of fat ≈ 3,500 kcals 500 extra kcals/day × 7 days = GAIN 1 lb/week 500 deficit kcals/day × 7 days = LOSE 1 lb/week Create a calorie deficit through combined dietary, behavioral and physical activity strategies.  Maintained Lifestyle Weight Loss ► More likely to regain weight if you lose it quickly. ► More likely to maintain weight loss if you lose it slowly. Learn better habits and make lifestyle changes.  Notes on Dietary Strategies for Weight Loss ► Must eat a minimum amount of calories. It’s hard to get a nutritionally adequate diet on less than 1200 kcals/day. Super low kcal diet results in FAST weight loss = loss of muscle and lowers the basal metabolic rate ►Consider taking a multivitamin/mineral supplement if restricting food intake and unable to get adequate micronutrients from food. Influences on our Nutrition and Physical Activity are COMPLEX.  Drugs Prescriptions – have risks like any drug.  Before 2021, weight loss drugs were not very successful.  New class of drugs since 2021: GLP-1 receptor agonists. To date, very successful (see next slide). Over-the-counter (OTC) – many contain caffeine, others have various stimulants, thus have side effects. ®  alli – orilisat Intentionally causes fat malabsorption 32 FDA Approved Anti-Obesity Medications https://www.ncbi.nlm.nih.gov/books/NBK279038/ Science is RAPIDLY changing with these new drugs!  How do these new drugs work? ► Glucagon-like peptide 1 receptor agonists: designed to mimic the effects of GLP-1 in the body. https://www.nature.com/articles/s41569-023-00849-3  Opportunities and Challenges of GLP-1 medicines ► Success of these medications provides further evidence that obesity is a disease. Hope that it will reduce stigma. ► Currently problems with access to medicines: Insurance coverage Supplies are limited. Creating greater health disparity? ► Lifestyle factors still matter to reduce chronic disease risk!!  Surgical Interventions ►Bariatric Surgery: Surgically alter the GI tract to malabsorb (remove part of intestine) and/or prevent consumption (restrict size of stomach). Requirements: must have tried weight loss programs and failed, have a BMI ≥ 35, and are having health problems due to their weight. ►Liposuction A popular procedure that is primarily cosmetic (directly removes fat cells). 36  Bariatric Surgery ►Success rate varies based on the type of surgery. ►Can eliminate diabetes & hypertension in successful cases. ►Possible dangerous complications: Surgery! Can re-stretch your stomach. Can develop nutrient deficiencies. ►Insurance ►Successful cases usually have intense diet coaching. 38 Summary: Weight Maintenance and Loss ►The most successful lifestyle weight management strategies combine 3 strategies: dietary, physical activity, and behavior modifications. It is important to find a balance with this and quality of life! ►The new GLP-1 class of medications has been successful, but is still recommended in combination with lifestyle strategies. 39