Adipose Tissue EDDIE SMITHLEAH WAGNER LEAH SANDERSJONATHAN GRIMWOOD FWS

What is adipose tissue?  Groups of adipocytes (lipid filled cells) that are loosely held together by collagen fibers and connective tissue cells.  Functions  Source of energy  Heat insulation  Mechanical cushioning

What is adipose tissue?  Formed from pre-adipocytes  Fat cells that have not yet been filled with lipids  Already present in adipose tissues  Can grow through adult life  One capillary per adipocyte for improved metabolism  Fat is primarily an energy source  Storing energy as another source would be inefficient and limit mobility  “Buffer” when energy expenditure is greater than energy intake

Composition of Adipose Tissue  Two Types  White fat cells – most common form; used for energy, insulation, and cushioning  Brown fat cells – metabolically less active; primary function is to generate body heat; can be activated with cold exposure  Unilocular vs. multilocular  Uni – single, larger lipid droplet   Multi – many smaller droplets

Composition of Adipose Tissue  60-85%  Lipids  90-99%  Triglycerides  Fatty Acids: myristic, palmitic, palmitoleic, stearic, oleic, linoleic  Others: FFA, diglycerides, cholesterol, phospholipids, cholesterol ester, monoglycerides (change based on diet)  5-30%  Water  2-3%  Protein

How much resides in average adult?  Normal weight adults can have between 15-30% of adipose tissue  Current average is 28-40% body fat, due to recent obesity epidemic.  Even those with normal BMI had high fat %  Lower BMI/weighing less does not always mean healthier Mean Percentage Body Fat, by Age Group and Sex --- National Health and Nutrition Examination Survey (NHANES), United States,

How much resides in average adult? Mean Percentage Body Fat, by Age Group and Sex --- National Health and Nutrition Examination Survey (NHANES), United States, Ranges Based on Age  Male  yo average %  yo average %  Female  8-11 yo average %  yo average %

How average percentages differ? American Council on Exercise

How much resides in average adult?  Essential levels of fat are necessary for insulation, protection, and energy purposes  Body uses fat for energy when at rest  Lack of sufficient fat stores will prevent the body from efficiently providing energy to the cells

Where can adipose tissue be found?  Subcutaneous – directly under the deepest layer of skin; insulation  Visceral – near organs; directly related to CVD & Hypertension

Distribution  Men – Android/”Apple”  Upper body  Waist  Abdomen  Women – Gynoid/”Pear”  Lower body  Hips  Thighs  Buttocks Note: Android/”Apple” storage sites are considered to be more dangerous to health because of fat location in relation to important organs.

Determining factors of distribution  Genetics  Family history is a great predictor of fat distribution patterns  Gender  Male – Upper body (“Apple”)  Female – Lower body (“Pear”)  Age  An increase in upper body/visceral fat has been observed in older women.  “Yo-yo dieting”  May increase upper body fat distribution Am J Clin Nutr Jul;66(1):111-5