Lipids are used by organisms for energy storage, as a signalling molecule e. Examples of common lipids include butter, vegetable oil, cholesterol and other steroids, waxes, phospholipids, and fat-soluble vitamins. The Nutrition Source, a website maintained by the Department of Nutrition at the Harvard School of Public Healthsummarizes the current evidence on the impact of dietary fat: "Detailed research—much of it done at Harvard—shows that the total amount of fat in the diet isn't really linked with weight or disease.
In animals and archaeathe mevalonate pathway produces these compounds from acetyl-CoA,  while in plants and bacteria the non-mevalonate pathway uses pyruvate and glyceraldehyde 3-phosphate as substrates.
Rather, weight gain is a consequence of excess consumption of any type of food, combined with metabolic factors. Carotenoids are important simple isoprenoids that function as antioxidants and as precursors of vitamin A. Fats are more common in animals, while oils are prevalent in plants and fish.
This involves the synthesis of fatty acids from acetyl-CoA and the esterification of fatty acids in the production of triglycerides, a process called lipogenesis. Unlike the case of genes and proteins which are primarily composed of linear combinations of 4 nucleic acids and 20 amino acids, respectively, lipid structures are generally much more complex due to the number of different biochemical transformations which occur during their biosynthesis.
The saccharolipid SL category was created to account for lipids in which fatty acyl groups are linked directly to a sugar backbone.