Lipid Metabolism Fat can be stored or used for energy Storage as fat –Adipose tissue –LPL = lipoprotein lipase Copyright 2005 Wadsworth Group, a division of Thomson Learning

Lipid Metabolism Fat (Adipose) cells –Increase in size = hypertrophy –Increase in number = hyerplasia –Increase in number mainly in adolescence but can happen in very obese adults –In severly obese adults, excess fat can be stored in other organs such as liver pancreas or muscle tissue –When you lose fat only the size of fat cells reduces not number

Lipid Metabolism Adipose tissue isnt passive –It sends signals to the rest of the body and the brain to ensure survival –Fat cells secrete more than a dozen proteins that trigger changes throughout the body –The amounts of various proteins that are released depends on whether the fat cells are expanding or contracting

Lipid Metabolism Four types of proteins have been studied –Leptin Suppresses appetite and induces body to burn more calories Bigger fat cell more leptin - but when you lose weight leptin amount goes down so weight loss is stalled With lower leptin levels you can feel more hungry –Adiponectin “ Good guy” hormone enables insulin to move sugar out of the blood into tissues More fat less adiponectin is produced –Ghrelin Makes you hungry Weight loss induces an increase in the amount of ghrelin released by the stomach –Inflammatory proteins Fat cells release inflammatory proteins such as interleukin-6 causing low level inflammation Inflammation is associated with rupturing plaques (fat deposited) in the arteries leading to heart attack or stroke

Lipid Metabolism Using fat for energy –Hormone-sensitive lipase –Provides very little glucose –But provides lots of energy (60% of the energy needs during rest) –Since very little glucose can be provided from fat, prolonged starvation is dangerous to nevous system Copyright 2005 Wadsworth Group, a division of Thomson Learning

Health Effects of Lipids Blood lipid profile Total cholesterol <200mg/dL LDL cholesterol <100mg/dL HDL cholesterol > or = 60mg/dL Triglycerides <150mg/dL Heart disease –Atherosclerosis (deposition of cholesterold etc on artery walls –Restricts blood flow, increases blood pressure Copyright 2005 Wadsworth Group, a division of Thomson Learning

Health Effects of Lipids Risks from saturated fats –More saturated fats higher the LDL Risks from trans fats –Trans fats affect blood lipids same way as saturated fats Risks from cholesterol –Affects blood cholesterol but not as strongly as saturated and trans fats Copyright 2005 Wadsworth Group, a division of Thomson Learning

High-Fat Foods Limit fatty meats, milk products, and tropical oils Copyright 2005 Wadsworth Group, a division of Thomson Learning

Dietary Cholesterol Copyright 2005 Wadsworth Group, a division of Thomson Learning

Health Effects of Lipids

Benefits from monounsaturated fats and polyunsaturated fats –Good for replacing saturated fats –Bring phytochemicals which are heart healthy Benefits from omega-3 fats –Prevent blood clots, –protect against irregular heartbeats, –lower blood pressure Balance omega-6 and omega-3 intakes –More fish less meat –Even one fish meal a month can show changes –But eat fresh fish (not fast food or frozen fried) Copyright 2005 Wadsworth Group, a division of Thomson Learning

Essential Fatty Acids Copyright 2005 Wadsworth Group, a division of Thomson Learning

Health Effects of Lipids Cancer –Links are not very clear –Omega-3 fats may have some protective effect Obesity –Increased calories in increasing fat intake –Inactivity makes it worse –But low fat may not necessarily mean low-calorie so beware! Copyright 2005 Wadsworth Group, a division of Thomson Learning

Recommended Intakes of Fat DRI: 20% - 35% of energy intake Linoleic acid AI –5% - 10% of energy intake Linolenic acid AI – % of energy intake Copyright 2005 Wadsworth Group, a division of Thomson Learning

Guidelines to Groceries Meats and meat alternatives –User leaner cuts of meat (round or loin cuts) –Meat alternatives like soy are heart healthy Milk and milk products –Low fat or skim milk products –Fermented milk products introduce good bacteria that produce fatty acids from fiber that reduce cholesterol synthesis in the liver Vegetables, fruits, and grains –Vitamins that are important in heart health –Fiber eliminates some cholesterol and fat Invisible fat –Visible fat in things like butter or fat on meats –Invisible fat in things like cheese or marbled fat –Keep invisible fats in mind when choosing foods Copyright 2005 Wadsworth Group, a division of Thomson Learning

Cutting Fat Cuts kCalories and Saturated Fat Copyright 2005 Wadsworth Group, a division of Thomson Learning

Guidelines to Groceries Limit foods with hydrogenated fats –Reduces saturated fats –Reduces Trans fat Cook with olive oil –Monounsaturated fatty acids Nibble on nuts –Omega-3 Feast on fish –But beware of mercury –Omega-3 Read food labels Copyright 2005 Wadsworth Group, a division of Thomson Learning

High-Fat Foods Changing guidelines for fat intake Copyright 2005 Wadsworth Group, a division of Thomson Learning

Guidelines to Groceries Fat replacers –Artificial fat Made from carbohydrates, proteins or fats Olestra –Sucrose attached to six or eight fatty acids –Body cannot break the bonds of olestra –Can bind some vitamins but can be overcome by supplementation –But some people experience symptoms like cramping and diarrhea Copyright 2005 Wadsworth Group, a division of Thomson Learning

High-Fat Foods Mediterranean diet –Olive oil –Lots of grains and vegetables –Less meat, more legumes, fish and poultry –Grass fed free ranging cows, chickens Mediterranean diet Low in saturated fats Very low in trans fat Rich in unsaturated fat Rich in complex carbohydrates and fiber Rich in nutrients and phytochemicals Copyright 2005 Wadsworth Group, a division of Thomson Learning