Those who adapt with changing times are most likely to survive. Throughout life our body becomes more efficient in some ways and less in others and we have to recognize that eating and doing things also have to change. Wisdom can increase, social skills tend to increase with greater age, staying active physically and socially helps.
With increased age muscle breakdown may become increased and rebuilding less efficient so even though appetite might be reduced it is important to have adequate protein foods each day. For ideal rebuilding/maintenance of muscles and other protein structures it can help to have the equivalent of 2-3 ounces of high quality protein food at breakfast, lunch and dinner rather than having a carbohydrate loaded breakfast and large serving of protein at dinner. To reduce the risk of muscle loss about 20 grams of protein per meal is recommended - more than in a typical toast or cereal breakfast and less than in a typical steak dinner.
Some links and more information about protein serving sizes see: Make every day Kidney Appreciation Day. Older people may benefit from slightly more protein than the standard recommendation, "1.0 to 1.3 g/kg/day dietary protein," may help prevent loss of muscle mass (called sarcopenia) which is not uncommon later in life. (1)
Eggs are a good source of protein and the yolk has beneficial nutrients in addition to protein. Cholesterol is not as harmful to the average person's health as was previously believed and adequate cholesterol levels are actually protective compared to having very low or elevated levels. Adequate cholesterol may help with maintaining nerve cell myelination in the brain and body (2) which is needed for memory and physical sensation.
It also helps maintain muscle mass and stronger bone mass to do both weight lifting type exercise and aerobic walking, biking, or other active work like gardening and doing housework at a brisk pace.
Disclaimer: Opinions are my own and the information is provided for educational purposes within the guidelines of fair use. While I am a Registered Dietitian this information is not intended to provide individual health guidance. Please see a health professional for individual health care purposes.
Nowson C, O'Connell S. Protein Requirements and Recommendations for Older People: A Review. Nutrients. 2015;7(8):6874-99. Published 2015 Aug 14. doi:10.3390/nu7085311, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4555150/
Berghoff SA, Gerndt N, Winchenbach J, et al. Dietary cholesterol promotes repair of demyelinated lesions in the adult brain. Nat Commun. 2017;8:14241. Published 2017 Jan 24. doi:10.1038/ncomms14241 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5286209/