Abstract: Objective To investigate and analyze the actual intake of protein and energy in adult patients with severe burns during post burn days (PBDs) 3 to 14. Methods Records of 52 adult patients with severe burns [37 males and 15 females, (37±9) years old], admitted to the Department of Plastic Surgery and Burns of Tianjin First Central Hospital from January 1st 2011 to December 31st 2017 and meeting the study inclusion criteria, were retrospectively analyzed. Nutrition intake from routes of oral diet, enteral nutrition preparations, and parenteral nutrition preparations of patients during PBDs 3 to 14 were obtained from critical care records. During PBDs 3 to 7 and PBDs 8 to 14, the personal daily total energy intake and the ratio of it to energy target of patients were calculated and compared; the personal daily intake of carbohydrate, fat, and protein and calorigenic percentages of carbohydrate, fat, and protein accounted for total energy intake, and the ratios of non-protein calories to total nitrogen of patients were calculated and compared; the personal daily energy and protein intake of patients from routes of oral diet, enteral nutrition preparations, and parenteral nutrition preparations were analyzed; the percentages of energy intake from routes of oral diet, enteral nutrition preparations, and parenteral nutrition preparations accounted for total energy intake, and the percentages of protein intake from routes of oral diet, enteral nutrition preparations, and parenteral nutrition preparations accounted for total protein intake of patients were calculated. Vomiting and diarrhea of patients during PBDs 3 to 7 and PBDs 8 to 14 were recorded. Levels of serum albumin, prealbumin, blood glucose, and triglycerides, 24-hour excretion of urinary nitrogen, nitrogen balance values of patients on PBDs 7 and 14 were recorded or calculated. Data were processed with paired t test and chi-square test. Results (1) The personal daily total energy intake of patients during PBDs 3 to 7 and PBDs 8 to 14 were (8 696±573) and (11 980±1 259) kJ respectively, and ratios of them to energy target [(13 290±1 561) kJ] were 65.4% and 90.1% respectively. The personal daily total energy intake of patients during PBDs 3 to 7 was obviously lower than that during PBDs 8 to 14 (t=18.172, P<0.01). (2) The personal daily intake of carbohydrate, fat, and protein of patients during PBDs 8 to 14 were obviously higher than those during PBDs 3 to 7 (t=15.628, 22.231, 10.403, P<0.01). The personal daily calorigenic percentages of carbohydrate, fat, and protein accounted for total energy intake of patients were 56.8%, 25.1%, and 18.3% respectively during PBDs 3 to 7 and 54.2%, 27.0%, and 18.7% respectively during PBDs 8 to 14. The calorigenic constituent ratio of personal daily intake of carbohydrate, fat, and protein accounted for total energy intake of patients during PBDs 3 to 7 was close to that during PBDs 8 to 14 (χ²=0.185, P>0.05). The ratios of non-protein calories to total nitrogen (kJ∶g) of patients during PBDs 3 to 7 and PBDs 8 to 14 were 469∶ 1 and 456∶ 1 respectively. (3) The personal daily energy intake of patients from routes of oral diet and parenteral nutrition preparations during PBDs 8 to 14 [(4 394±978), (5 723±898) kJ] were obviously higher than those during PBDs 3 to 7 [(2 137±453), (4 855±825) kJ, t=26.516, 6.583, P<0.01], while the personal daily energy intake of patients from routes of enteral nutrition preparations during PBDs 8 to 14 was close to that during PBDs 3 to 7 (t=1.922, P>0.05). The constituent ratio of personal daily energy during PBDs 3 to 7 was close to that during PBDs 8 to 14 (χ²=4.100, P>0.05). The personal daily protein intake of patients from route of oral diet during PBDs 8 to 14 was (58±22) g, obviously higher than (25±6) g during PBDs 3 to 7 (t=14.514, P<0.01). The personal daily protein intake of patients from routes of enteral nutrition preparations and parenteral nutrition preparations during PBDs 8 to 14 was close to those during PBDs 3 to 7 (t=1.924, 1.110, P>0.05). The constituent ratio of personal daily protein intake from routes of oral diet, enteral nutrition preparations, and parenteral nutrition preparations accounted for total protein intake during PBDs 8 to 14 was close to that during PBDs 3 to 7 (χ²=5.634, P>0.05). (4) There were 3 patients with vomiting and 4 patients with diarrhea during PBDs 3 to 7, and 1 patient experienced both of them during PBDs 8 to 14. The levels of serum albumin, prealbumin, blood glucose, and triglycerides, 24-hour excretion of urinary nitrogen, and nitrogen balance values of patients on PBDs 7 and 14 were (29±4) and (30±4) g/L, (132±42) and (171±48) mg/L, (7.4±2.8) and (6.7±2.8) mmol/L, (1.5±0.7) and (1.4±0.7) mmol/L, (30.5±4.3) and (34.5±2.2) g, -(25.1±2.6) and -(23.7±3.9) g, respectively. Conclusions The personal daily total energy intake of patients during PBDs 3 to 7 was lower than that during PBDs 8 to 14. The calorigenic constituent ratio of personal daily intake of carbohydrate, fat, and protein accounted for total energy of patients during PBDs 3 to 7 was close to that during PBDs 8 to 14. Energy and protein intake were mostly derived from parenteral nutrition preparations during PBDs 3 to 7, while those during PBDs 8 to 14 were mainly derived from parenteral nutrition preparations and oral diet.