Table of ContentsView AllTable of ContentsEarly SymptomsLater SymptomsMalnutritionComplicationsWhen to Get Help
Table of ContentsView All
View All
Table of Contents
Early Symptoms
Later Symptoms
Malnutrition
Complications
When to Get Help
The first symptoms of not eating can include fatigue, difficulty concentrating, and nausea, in part due tohypoglycemia(low blood sugar). As time goes on, more severe symptoms like slurred speech, confusion, fainting (syncope), and even seizures may occur.
Long-term lack of food can lead tomalnutrition, which manifests as thinning hair, skin changes, muscle loss, frequent illness, infertility, and in extreme cases,cachexia(wasting).The exact symptoms one experiences can vary, based on age, general health, and how long it has been since you last ate.
Verywell / Ellen Linder
When you are in afasted state(meaning you have stopped eating), your body’s metabolism slows down. Metabolism is the process of converting the calories from food into energy.
One of the most immediate effects of not eating ishypoglycemia, in which your body’s main source of energy—glucose (blood sugar)—drops steeply. The lack of fuel can trigger an array of side effects, including:
Eating food, particularlysimple carbohydrates, can reverse hypoglycemia and these symptoms relatively quickly.
Symptoms of Prolonged Fasting
The process of conversion is known asketosis, which can trigger symptoms like:
If you are entirely without food, the process of ketosis typically occurs within 72 hours.If you are eating too little food, it may take longer.
At the same time, the emptying of the body’s glucose reserves can lead to symptoms of severe hypoglycemia, including:
How Long Can a Human Go Without Eating?Experts believe humans can generally survive for up to two monthswithout eating food. Survival time may be slightly more or less, depending on individual factors like how much body fat you have at the start, your hydration levels, and general health.
How Long Can a Human Go Without Eating?
Experts believe humans can generally survive for up to two monthswithout eating food. Survival time may be slightly more or less, depending on individual factors like how much body fat you have at the start, your hydration levels, and general health.
Complications of Not Eating
One of the longer-term complications of not eating enough is malnutrition. Malnutrition occurs when you either do not eat not have enough to eat, are not eating enough of the right things, or are not absorbing nutrients from foods you eat.
When the body continues to become deficient in calories, it cannot receive all of the carbohydrates, proteins, fats, vitamins, and minerals it needs to keep the body functioning normally.
You may be malnourished if you unintentionally lose 5% to 10% of your body weight within three to six months or yourbody mass index (BMI)is under 18.5.BMI, however, is a dated, flawed measure; it doesn’t take into account factors such asbody composition, ethnicity, sex, race, and age.
Even though it is abiased measure, BMI is still widely used in the medical community because it’s an inexpensive and quick way to analyze a person’s potential health status and outcomes.
When this weight loss happens, symptoms of malnutrition can develop, including:
Rare Symptoms
The prolonged absence of nutrition causes the body to decline. A person may start experiencing long-term symptoms of malnutrition such as:
How Much Food Is Too Little ?TheDietary Guidelines for Americansrecommends that adult females get at least 1,600 calories a day and adult males get at least 2,200 calories a day.These are the minimum values for weight maintenance. Anything less may deprive you of the nutrients you need to function normally.
How Much Food Is Too Little ?
TheDietary Guidelines for Americansrecommends that adult females get at least 1,600 calories a day and adult males get at least 2,200 calories a day.These are the minimum values for weight maintenance. Anything less may deprive you of the nutrients you need to function normally.
Infants and Young Children
Infants and children have key differences in their metabolism that make them use up more protein, glucose, and lipids to maintain their baseline energy. This can cause them to show symptoms of not eating more quickly than adults.
Infants and children who are not getting enough to eat may be lethargic (not responsive), sleep more than normal, and be fussy or irritable.
Teenagers
Teens may have delayed growth or appear short in stature. They may also lack the usual symptoms of puberty due to disruptions in hormones from lack of glucose and calories.
Decreased caloric intake in older children and teens may also cause fragile bones, learning difficulties, and mood problems (like depression or irritability).
People With Chronic Conditions
People with certain chronic conditions may have a greater demand for nutrition. These include conditions like:
What Are the Three Stages of Starvation?
When to See a Healthcare Provider
If you are experiencing any of the following after a period of not eating, seek immediate emergency care:
Summary
Symptoms of not eating can develop due to hypoglycemia and ketosis, causing mild symptoms like fatigue and dizziness to more serious ones like heart palpitations and seizures. A common complication of not eating is malnutrition, which can lead to missed periods, infertility, bone mineral loss, and severe wasting.
Children who are malnourished are at risk of brittle bones, learning difficulties, and depression. People with chronic diseases may need additional nutrition to meet the body’s demand for calories, protein, minerals, and other nutrients.
16 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Centers for Disease Control and Prevention.Low blood sugar (hypoglycemia).John Hopkins Medicine.Anorexia Nervosa.Bulik C, Carroll I, Mehler P.Reframing anorexia nervosa as a metabo-psychiatric disorder.TEM. 2021 Oct;32(10):752-761. doi:10.1016/j.tem.2021.07.010Scott JM, Deuster PA.Ketones and human performance.J Spec Oper Med. 2017;17(2):112-116. doi:10.55460/PGWG-H55JHarvard Health Publishing.What is keto flu?.Elliot B, Mina M, Ferrier C.Complete and voluntary starvation of 50 days.Clin Med Insights Case Rep. 2016;9:67-70. doi:10.4137/CCRep.S39776National Health Service (UK).Symptoms-malnutrition.Johns Hopkins Medicine.Malnutrition.Office of Disease Prevention and Health Promotion.Current dietary guidelines. In:Dietary Guidelines for American 2020-2025.Khan F, Fisher J, Sparks E, Jaksic T.Metabolism of infants and children.Pediatric Surg. 2020:231-243. doi:10.1007/978-3-662-43588-5_15John Hopkins Medicine.Failure to thrive.Beirer A.Malnutrition and cancer, diagnosis and treatment.Magazine Eur Med Oncol. 2021;14(2):168-173. doi:10.1007/s12254-020-00672-3Umeakunne K, Hibbert J.Nutrition in sickle cell disease: recent insights.Nutr Diet Suppl. 2019;11:9-17. doi:10.2147/nds.s168257Crohn’s and Colitis Foundation.Malnutrition and IBD.Steinhauser M, Olenchock B, O’Keefe J, et al.The circulating metabolome of human starvation.JCI Insight. 2018 Aug;3(16):e121434. doi:10.1172/jci.insight.121434MedlinePlus.When to use the emergency room - adult.
16 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Centers for Disease Control and Prevention.Low blood sugar (hypoglycemia).John Hopkins Medicine.Anorexia Nervosa.Bulik C, Carroll I, Mehler P.Reframing anorexia nervosa as a metabo-psychiatric disorder.TEM. 2021 Oct;32(10):752-761. doi:10.1016/j.tem.2021.07.010Scott JM, Deuster PA.Ketones and human performance.J Spec Oper Med. 2017;17(2):112-116. doi:10.55460/PGWG-H55JHarvard Health Publishing.What is keto flu?.Elliot B, Mina M, Ferrier C.Complete and voluntary starvation of 50 days.Clin Med Insights Case Rep. 2016;9:67-70. doi:10.4137/CCRep.S39776National Health Service (UK).Symptoms-malnutrition.Johns Hopkins Medicine.Malnutrition.Office of Disease Prevention and Health Promotion.Current dietary guidelines. In:Dietary Guidelines for American 2020-2025.Khan F, Fisher J, Sparks E, Jaksic T.Metabolism of infants and children.Pediatric Surg. 2020:231-243. doi:10.1007/978-3-662-43588-5_15John Hopkins Medicine.Failure to thrive.Beirer A.Malnutrition and cancer, diagnosis and treatment.Magazine Eur Med Oncol. 2021;14(2):168-173. doi:10.1007/s12254-020-00672-3Umeakunne K, Hibbert J.Nutrition in sickle cell disease: recent insights.Nutr Diet Suppl. 2019;11:9-17. doi:10.2147/nds.s168257Crohn’s and Colitis Foundation.Malnutrition and IBD.Steinhauser M, Olenchock B, O’Keefe J, et al.The circulating metabolome of human starvation.JCI Insight. 2018 Aug;3(16):e121434. doi:10.1172/jci.insight.121434MedlinePlus.When to use the emergency room - adult.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Centers for Disease Control and Prevention.Low blood sugar (hypoglycemia).John Hopkins Medicine.Anorexia Nervosa.Bulik C, Carroll I, Mehler P.Reframing anorexia nervosa as a metabo-psychiatric disorder.TEM. 2021 Oct;32(10):752-761. doi:10.1016/j.tem.2021.07.010Scott JM, Deuster PA.Ketones and human performance.J Spec Oper Med. 2017;17(2):112-116. doi:10.55460/PGWG-H55JHarvard Health Publishing.What is keto flu?.Elliot B, Mina M, Ferrier C.Complete and voluntary starvation of 50 days.Clin Med Insights Case Rep. 2016;9:67-70. doi:10.4137/CCRep.S39776National Health Service (UK).Symptoms-malnutrition.Johns Hopkins Medicine.Malnutrition.Office of Disease Prevention and Health Promotion.Current dietary guidelines. In:Dietary Guidelines for American 2020-2025.Khan F, Fisher J, Sparks E, Jaksic T.Metabolism of infants and children.Pediatric Surg. 2020:231-243. doi:10.1007/978-3-662-43588-5_15John Hopkins Medicine.Failure to thrive.Beirer A.Malnutrition and cancer, diagnosis and treatment.Magazine Eur Med Oncol. 2021;14(2):168-173. doi:10.1007/s12254-020-00672-3Umeakunne K, Hibbert J.Nutrition in sickle cell disease: recent insights.Nutr Diet Suppl. 2019;11:9-17. doi:10.2147/nds.s168257Crohn’s and Colitis Foundation.Malnutrition and IBD.Steinhauser M, Olenchock B, O’Keefe J, et al.The circulating metabolome of human starvation.JCI Insight. 2018 Aug;3(16):e121434. doi:10.1172/jci.insight.121434MedlinePlus.When to use the emergency room - adult.
Centers for Disease Control and Prevention.Low blood sugar (hypoglycemia).
John Hopkins Medicine.Anorexia Nervosa.
Bulik C, Carroll I, Mehler P.Reframing anorexia nervosa as a metabo-psychiatric disorder.TEM. 2021 Oct;32(10):752-761. doi:10.1016/j.tem.2021.07.010
Scott JM, Deuster PA.Ketones and human performance.J Spec Oper Med. 2017;17(2):112-116. doi:10.55460/PGWG-H55J
Harvard Health Publishing.What is keto flu?.
Elliot B, Mina M, Ferrier C.Complete and voluntary starvation of 50 days.Clin Med Insights Case Rep. 2016;9:67-70. doi:10.4137/CCRep.S39776
National Health Service (UK).Symptoms-malnutrition.
Johns Hopkins Medicine.Malnutrition.
Office of Disease Prevention and Health Promotion.Current dietary guidelines. In:Dietary Guidelines for American 2020-2025.
Khan F, Fisher J, Sparks E, Jaksic T.Metabolism of infants and children.Pediatric Surg. 2020:231-243. doi:10.1007/978-3-662-43588-5_15
John Hopkins Medicine.Failure to thrive.
Beirer A.Malnutrition and cancer, diagnosis and treatment.Magazine Eur Med Oncol. 2021;14(2):168-173. doi:10.1007/s12254-020-00672-3
Umeakunne K, Hibbert J.Nutrition in sickle cell disease: recent insights.Nutr Diet Suppl. 2019;11:9-17. doi:10.2147/nds.s168257
Crohn’s and Colitis Foundation.Malnutrition and IBD.
Steinhauser M, Olenchock B, O’Keefe J, et al.The circulating metabolome of human starvation.JCI Insight. 2018 Aug;3(16):e121434. doi:10.1172/jci.insight.121434
MedlinePlus.When to use the emergency room - adult.
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