Efficacy of Intermittent or Continuous Very Low-Energy Diets in Overweight and Obese Individuals with Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analyses
Table 1
Characteristics of included studies.
Study ID
Study type
Interventions (kcal/day)
Comparator (kcal/day)
Use of hypoglycemic drugs
Study duration
VLED
Control
Treatment
Follow-up
Anderson 1994
RCT
VLED (800): at least five liquid supplements/day which provide 800 kcal with 80 g of high-quality protein+two vitamin/mineral tablets
LED (approximately 820): at least three supplements/day which provide 320 kcal and 32 g of high-quality protein, one vitamin/mineral tablet, recommended evening meal of approximately 500 kcal and 50 g of high-quality protein
Unclear
Unclear
3 months
1 year
Carter 2016
RCT
Intermittent VLED (400-598): 1670-2500 kJ/day for 2 days each week, with the remaining 5 days as habitual eating
LED (1196-1555): continuous energy restriction diet of 5000-6500 kJ/day
Medications adjusted according to blood glucose level
12 weeks
None
Carter 2018
RCT
VLED (500-600): an intermittent energy restriction diet (500-600 kcal/d) followed for 2 nonconsecutive days per week (participants followed their usual diet for the other 5 days)
LED (1200-1500): a continuous energy restriction diet (1200-1500 kcal/d) followed for 7 days per week
Medications could be reduced depending on glucose
12 months
2 years
Carter 2019
RCT
VLED (500-600): an intermittent energy restriction diet (500-600 kcal/d) followed for 2 nonconsecutive days per week (participants followed their usual diet for the other 5 days)
LED (1200-1500): a continuous energy restriction diet (1200-1500 kcal/d) followed for 7 days per week
Medications could be reduced depending on glucose
12 months
2 years
Harvey 1993
RCT
VLED (400-500): during weeks 1-12, consumed a 400-500 kcal/day. This was followed by a 6-week refeeding period, which required slow reintroduction of calories, carbohydrate, and fat. By the end of the 6 weeks of refeeding, subjects in the VLED were prescribed a self-selected balanced, low-calorie diet (1000-1200 kcal/day)
LED (1000-1200): a self-selected balanced diet of 1000-1200 kcal per day for 6 months
15 of the subjects were treated with diet only, 54 with oral medication, and 23 with insulin.
24 week
None
Wing 1991
RCT
VLED (400-500): weeks 0–4: 1000–1500 kcal/day; weeks 5–12: 400–500 kcal/day; weeks 13–20: 1000 kcal/day; weeks 21–72 : 1000–1500 kcal/day (weight maintenance). Included a 20-week behavioural treatment programme with weekly group meetings including instructions on behavioural modification, exercise, and diet
LED (1000–1500): weeks 0-20: 1000–1500 kcal/day (intervention period); weeks 21-72: 1000–1500 kcal/day (weight maintenance). Included a 20-week behavioural treatment programme with weekly group meetings including instructions on behavioural modification, exercise, and diet
Unclear
Unclear
20 weeks
1 year
Wing 1994
RCT
VLED (400-500): weeks 0–12 and 24-36: 400–500 kcal/d+vitamins and supplements, otherwise 1000-1200 kcal/d. Included a 50-week behavioural treatment programme with weekly group meetings including instructions on behavioural modification, exercise, and diet
LED (1000-1200): weeks 0-48: 1000-1200 kcal/d (intervention period); subjects were encouraged to keep their fat intake below 30% of the daily calorie intake. Included a 50-week behavioural treatment programme with weekly group meetings including instructions on behavioural modification, exercise, and diet
Unclear
Unclear
1 year
2 years
Jackness 2013
NRCT
VLED (300-500): day 1: 360 kcal/day; days 2–24: 500 kcal/day
RYGB (500): postoperative VLED is assumed of approximately 500 kcal/day until the end of week 3
RYGB (<800): first 5 days after RYGB operation: <600 kcal/day; weeks 1–3: gradual increase to 700–800 kcal/day; week 3–month 3: 1200 kcal/day
Unclear
Unclear
3 months
None
Plum 2011
NRCT
VLED (800): the diet divided into five servings of 160 kcal (800 kcal/day) in 237 ml per serving
RYGB: postintervention, subjects followed dietary instructions provided by the surgical team
55% reduction in the number of medications after LCD
Antidiabetic medications were discontinued after RYGB
VLED: 8.1 (0.5) weeks RYGB: 3.4 (0.3) weeks
None
Cinkajzlova 2018
NRCT
VLED (595): total energy content of 2500 kJ/day for 3 weeks
Surgery: the procedures included gastric plication (10 subjects), gastric banding (2 subjects), and gastric bypass (1 subject)
Unclear
Unclear
VLCD 3 weeks; control 1 m, 3 m, and 1 y
None
Steven 2016
RCT
VLED (700): the VLED provided an average of 700 kcal/day
RYGB (~800): the postoperative (RYGB) diet was water only on day 1 then a semisolid diet (~800 kcal/day) for the rest of the first week.
Participants were asked to stop medications prior to the first study: metformin and/or sulphonylureas for at least 72 h, dipeptidyl peptidase-4 inhibitors for 1 month, and insulin for at least 24 h
7 days
None
Paisey 1995
NRCT
VLED (400-670): 400-470 kcal/d for women, 540–670 kcal/d for men for 3-5 months and repeated in the course of the study if appropriate. Once an agreed target weight had been reached, patients were seen intensively to wean them back onto a low-fat diet. A standardized programme of low-fat, low-refined carbohydrate foods was introduced over a 6-week period as patients transferred from VLED to normal eating patterns. They were advised to continue low-fat nutrition in the long term with three main meals daily
MER: low-fat, low-sugar, and high-fibre intake advised; 5-day self-report food records were collected and discussed individually, repeated every 6-8 weeks. Aerobic exercises with encouragement performed at each visit followed by a group discussion on nutrition
All antidiabetic medication was stopped on day one, and insulin dosage halved. Hypotensive and hypolipidemic agents were stopped if appropriate at one month
Unclear
6 months
None
Paisey 1998
NRCT
Same as “Paisey 1995”
Same as “Paisey 1995”
Subjects were advised to stop all antidiabetic medication and diuretics from day 1 of treatment
Unclear
12 months
None
Paisey 2002
NRCT
Same as “Paisey 1995”
Same as “Paisey 1995”
Antidiabetic and antihypertensive medications were stopped during the first week of treatment
Unclear
At least 6 weeks
5 years
Li 2017
RCT
VLED (300): days 1~2: low-calorie diet (1200 kcal/day); from the evening of study day 3 to the evening of study day 11: 300 kcal/day; followed by 3 low-calorie diet days (1200 kcal/day), followed by advice about a Mediterranean diet. Fasting took place only once in the 4-month period
MER: follow the principles of a Mediterranean diet
Subjects were advised to abstain from other new treatments against diabetes during the study period
4 months
None
Williams 1998
RCT
VLED (400-600): 1500-1800 kcal/day diet, except for a total of 20 study days during which they consumed a 400-600 kcal/day VLED. (1-day): a VLED for 5 consecutive days during week 2 of the study and then 1 day a week for 15 weeks, subjects used diaries to record daily caloric intake
MER (1500-1800): a 1500-1800 kcal/day diet throughout the 20 weeks of the treatment programme. Included a 20-week behavioural treatment programme with weekly group meetings including instructions on behavioural modification, exercise, and diet. Subjects used diaries to record daily caloric intake
Unclear
Unclear
20 weeks
None
Williams 1998a
RCT
VLED (400-600): 1500-1800 kcal/day diet, except for a total of 20 study days during which they consumed a 400-600 kcal/day VLED. (5-day): a VLED for 5 consecutive days during weeks 2, 7, 12, and 17+a 20-week behavioural treatment programme with weekly group meetings including instructions on behavioural modification, exercise, and diet. Subjects used diaries to record daily caloric intake
MER (1500-1800): a 1500-1800 kcal/day diet throughout the 20 weeks of the treatment programme. Included a 20-week behavioural treatment programme with weekly group meetings including instructions on behavioural modification, exercise, and diet. Subjects used diaries to record daily caloric intake
Unclear
Unclear
20 weeks
None
Laakso 1988
RCT
VLED (500-800): day 1-day 3: 30 kcal/kg/d; day 4-day 15: 500 kcal/d; day 15-day 17: 800 kcal/d
MER (30 kcal/kg/d): the diet was as previously described (30 kcal/kg/d) consisting of 50% carbohydrates, 30% fat, and 20% protein divided into three main meals
All medications for diabetes were discontinued
Insulin was started using intermediate-acting insulin as one single injection at 7 AM. The mean dosage of insulin (±SEM) was
