Lipids

• Examples of lipids include: fats, waxes, steroids, phospholipids
• The functions of lipids include:

  • Long term energy storage
  • Acting as a fat cushion to protect organs and joints
  • Surrounding neurons (nerve cells)
  • Helping to warm the body by storing fat under the skin
  • Steroids function as hormones and cholesterol
  • Phospholipids form the cell membrane
• Lipids are stored by the body due to the efficiency of carbon-hydrogen bonds in storing energy, making them ideal for long-term storage
• Lipids store more than twice the energy per gram than carbohydrates but are also twice as hard to get rid of, making weight loss challenging
• Three classes of lipids are:

  1. Fats

  2. Phospholipids

  3. Steroids
• Fats are made of fatty acids and glycerol
• Fats can be made of glycerol and two fatty acids (diglyceride) or three fatty acids (triglyceride)
• Fatty acids contain a carboxyl group (COOH) followed by a long chain of carbon atoms with hydrogen atoms
• Saturated fatty acids:

  • Contain only single bonds
  • Have a straight shape, making them tightly packed and solid at room temperature
  • Example: Palmitic acid
• Saturated fats:

  • Contain saturated fatty acids
  • Found in animal sources like red meat, dairy, lard, and butter
  • Solid at room temperature
  • Associated with health problems
• Unsaturated fatty acids:

  • Contain one or more double bonds
  • Monounsaturated have one double bond, while polyunsaturated have more than one
  • Have a kink or bend at each double bond, making them liquid at room temperature
  • Example: Linolenic acid
• Unsaturated fats:

  • Contain unsaturated fatty acids
  • Found in plants like olives, canola, corn, and some animals
  • Liquid at room temperature
  • More reactive than saturated fats
• Essential fatty acids:

  • Needed for cellular or body functions
  • Cannot be produced by our bodies and must come from the food we eat
  • Example: Linolenic acid and linoleic acid
• Phospholipids:

  • Form part of the cell membrane
  • Have a hydrophilic phosphate head and hydrophobic fatty acid tails
• Steroids:

  • Common structure linked to 4 carbon rings
  • Include sex hormones (estrogen, testosterone) and cholesterol
  • Anabolic steroids are artificial steroids
• Cholesterol:

  • Acts like a waxy fat
  • Mostly made and regulated by the liver
  • Functions include maintaining cell membrane strength, hormone and vitamin D production
• Low-density lipoprotein (LDL):

  • Known as bad cholesterol
  • Builds up in artery walls, blocks circulation, and increases heart attack risk
• High-Density Lipoprotein (HDL):

  • Known as good cholesterol
  • Removes LDL from arteries, carries it to the liver for metabolism, reducing heart attack risk
• Trans fat:

  • Found in meat or dairy products with saturated fat
  • Also present in processed foods (banned in Canada)
  • Created by hydrogenating unsaturated fats, negatively impacting cholesterol levels