TABLE 2.

Observational studies evaluating the effect of diets with different daily calorie intake and macronutrient composition on hepatic outcomes

Author	Country	n	Subjects	Duration	Intervention	kcal/day	CHO/day (g)	Fat/day (g)	Biochemistry	Imaging	Histology
Tendler et al. 47	USA	5	Obese, NAFLD	6 months	HFKD	Unr	<20	Unr	n/a	n/a	Improved
Perez‐Guisado et al. 48	Spain	14	MS, NAFLD	3 months	HFKD	Unr	<30	n/a	Improved	Improved (US)	n/a
Schiavo et al 49	Italy	27	Obese, NAFLD	1 month	HFKD	1200	12	91	Improved	Improved (US)	n/a
Mardinoglu et al 45	Sweden	17	MS, NAFLD	2 weeks	HFKD	3115	20–30	241*	Improved	Improved (MRS)	Improved
Paoli et al 50	Italy	106	Obese	6 weeks	VLCKD	1098	34	63	Unchanged	n/a	n/a
Paoli et al 44	Italy	81	Obese	20 days#	VLCKD	976	30	51	Unchanged	n/a	n/a
Basciani et al 51	Italy	24	Obese	6 months	VLCKD	700	50	10^	Improved	n/a	n/a
Leonetti et al 52	Italy	50	Obese	10 days#	VLCKD	577	15	24	Unchanged	Improved (US)	n/a
Colles et al 53	USA	32	Obese	12 weeks	VLCKD	456	45	7	Unchanged	Improved (CT, MRI)	n/a
Bruci et al 54	Italy	92	Obese	8 weeks#~	VLCKD	450–800	20–50	15–30	Unchanged	n/a	n/a
Benjaminov et al 55	Israel	14	Obese	4 weeks	LCD	~1520	~54	~94	Unchanged	Trend improved (CT)
Lewis et al 56	Australia	18	Obese	6 weeks	VLCD	450–800	n/a	n/a	n/a	Improved (MRS)	n/a
Schwenger et al 6	Canada	139	Obese	1 week	VLCD	900	67	30	n/a	n/a	Improved
Browning et al 57	USA	18	Healthy	48 hours	Fasting	0	0	0	Unchanged	Unchanged (MRS)	n/a
Wilhelmi de Toledo et al 58	Germany	1422	Overweight	4–21 days	Fasting	200–250	25–35	n/a	AST/ALT increase	n/a	n/a

Note. Data are expressed as mean; in case of studies in which data on macronutrient compositions were published in percentages (*), the relative grams of carbohydrate and fat were calculated considering the following assumption: 1 g of CHO = 3.8 kcal; 1 g of fat = 9.3 kcal, 1 g of protein = 4 kcal. When possible, authors were contacted to apply for unpublished data relating to diets composition (^). In case of studies (#) using multistep diet regimens, only the duration of the intervention phase of interest is reported. (~): reported data have a significant standard deviation, especially relative to CHO intake (54 ± 22 g/day); the study has been therefore categorized as nonketogenic.

Abbreviations: HFKD: high fat ketogenic diet; VLCKD: very low calorie ketogenic diet; LCD: low carbohydrate diet; VLCD: very low calorie diet; NAFLD: nonalcoholic fatty liver disease; MS: metabolic syndrome; unr: unrestricted; n/a: not available data; US: ultrasound examination; MRS: magnetic resonance spectroscopy; CT: computerized tomography; kcal/day: daily kilocalorie intake; CHO/day (g): carbohydrate daily intake in grams; fat/day (g): fat daily intake in grams.