Gastroenteritis: This is often the most common cause of acute nausea and vomiting, typically accompanied by other symptoms like diarrhea. The early satiety could be due to the inflammation of the stomach lining, reducing its capacity.

Pregnancy: Morning sickness is a classic symptom of early pregnancy, which can include nausea, vomiting, and changes in appetite or satiety.
Gastroparesis: A condition where the stomach takes too long to empty its contents, leading to nausea, vomiting, and feeling full after eating very little.
Peptic Ulcer Disease: Ulcers in the stomach or duodenum can cause nausea, vomiting, and early satiety due to pain and inflammation.
Food Poisoning: Similar to gastroenteritis, but usually with a more sudden onset and potentially more severe symptoms.

Appendicitis: Although it typically presents with abdominal pain, nausea, and vomiting, early satiety can be a symptom if the appendix is located near the stomach or duodenum, affecting digestion.
Pancreatitis: Inflammation of the pancreas can cause severe abdominal pain, nausea, vomiting, and changes in appetite or satiety.
Intestinal Obstruction: A blockage in the intestines can lead to severe vomiting, nausea, and early satiety due to the inability of food to pass through.
Myocardial Infarction: In some cases, a heart attack can present with nausea, vomiting, and a feeling of fullness or discomfort in the upper abdomen.

Zollinger-Ellison Syndrome: A rare disorder characterized by excessive gastric acid production, leading to severe peptic ulcers, diarrhea, and abdominal pain.
Cyclic Vomiting Syndrome: A condition with recurrent episodes of severe nausea and vomiting, often with no apparent cause.
Rumination Syndrome: A condition where food is regurgitated and then chewed and swallowed again, which can lead to nausea, vomiting, and early satiety.
Eosinophilic Gastroenteritis: A rare condition where eosinophils infiltrate the gastrointestinal tract, causing inflammation, nausea, vomiting, and abdominal pain.