Carbohydrates or starch polymers are formed by condensation which bonding together of monomers (monosaccharides) and loosing a molecule of water in the process. These polymers include glycogen and starch and they may be formed by aggregation of monomers in the cells assisted by enzymes.
Fat polymers are formed through the attachments of monomers such as alkyl or allyl chains, aliphatic or aromatic to one of the three hydroxyl groups of glycerol, consuming one or two or all 3 hydroxyl groups of glycerol now called mono, bi or triglycerides respectively.
Proteins polymers are compounds derived from amino acids monomers. Amino acids have carboxy snd sn smino group on the same carbon. The amino acids polymerize by condensation to form protein chains.
Size of the biomolecules is normally based on the molecules of concern, in this case i would state that fatty acids or fatty polymers usually have 4 to 28 carbon atoms, Starch contains about 30 glucose units (amylopectin) while number of amino acid units in a protein depends on the sequences of the bases in the gene that encode a particular protein.