Table 1.
Study characteristics of randomised trials of low-fat vs. low-carbohydrate dietary interventions.
| First Author | Randomised Participants | Country | Low-Fat Intervention | Low-Carb Intervention | Follow-Up Duration (Months) |
|---|---|---|---|---|---|
| Antonio De Luis, 2015 [29] | 331 | Spain | Standard protein hypocaloric: 55% carbohydrates, 27% fat, 20% protein | High Protein hypocaloric: 33% carbohydrate, 33% fat, 34% protein | 9 |
| Bazzano, 2014 [30] | 148 | USA | National Cholesterol Education Program Guidelines (<30% fat, 55% carbohydrates) | Low-carbohydrate diet | 12 |
| Bradley, 2009 [31] | 27 | UK | 20% fat, 60% carbohydrate; ~500 kcal calorie deficit | 60% fat, 20% carbohydrate; ~500 kcal calorie deficit | 1.84 |
| Brehm, 2003 [32] | 53 | USA | Energy-restricted, moderately low-fat diet with 55% carbohydrate, 15% protein, and 30% fat. | Ad libitum low carb, <20g carbohydrate/day; increase to 40–60 g/day if still in ketosis. | 6 |
| Brehm, 2005 [33] | 50 | USA | Energy-restricted, moderately low-fat diet with 55% carbohydrate, 15% protein, and 30% fat. | Ad libitum low carb, <20 g carbohydrate/day; increase to 40–60 g/day if still in ketosis. | 4 |
| Brinkworth, 2009 [34] | 118 | Australia | 30% fat; isocaloric | Energy restricted (6–7 megajoules) low-carbohydrate (4%, 35%, and 61% of energy as carbohydrate, protein, and fat) |
12 |
| Cornier, 2005 [35] | 44 | USA | 60% CHO, 20% fat, and 20% protein (high carbohydrate/low fat); energy restricted 400 kcal deficit | 40% carbohydrate 40% fat, and 20% protein (low carbohydrate/ high fat); energy restricted 400kcal deficit | 3.68 |
| Dale, 2009 [36] | 200 | New Zealand | High-monounsaturated fat diet; 25% protein, 21% monounsaturated fat, 40% carbohydrate (Nurse supported or Intensive supported) |
55% carbohydrates, 15–20% protein and 25–30% fat; encouraged to consume low-glycaemic food (Nurse supported or Intensive supported) |
24 |
| Dansinger, 2005 [37] | 160 | USA | Ornish, vegetarian diet containing 10% of calories from fat. | Atkins diet group, <20 g/day with gradual increase to 50 g/day | 12 |
| Foraker, 2014 [38] | 79 | USA | 60% carbohydrates, 20% fat, 20% protein | 40% carbohydrates, 30% fat, 30% protein | 18 |
| Foster, 2003 [24] | 63 | USA | 60% carbohydrate, 25% fat, and 15% protein | Atkins diet group, 20 g/day with gradual increase until stable | 12 |
| Foster, 2010 [39] | 307 | USA | 55% carbohydrates, 30% fat, 15% protein | Atkins diet group, 20 g/day for first 12 weeks with gradual of 5 g/day per week after | 24 |
| Frisch, 2009 [40] | 200 | Germany | >55% carbohydrate, <30% fat, 15% protein | <40% carbohydrates, >35% fat, 25% protein | 12 |
| Gardner, 2007 [41] | 311 | USA | (1) LEARN The LEARN group was instructed to follow a prudent diet that included 55% to 60% energy from carbohydrate <10% saturated fat (2) Ornish <10% fat |
Atkins, <20 g/d or less of carbohydrate for “induction” (usually 2–3 months) and 50 g/d or less of carbohydrate for the subsequent “ongoing weight loss” phase. | 12 |
| Gardner, 2016 [42] | 31 | USA | Reduced intake of fat to 20 g/day to achieve lowest level of fat during first 8 weeks; in the second stage slowly add fat in increments of 5 g/d and hold for 1–4 weeks before adding another 5 g/day; third stage to identify lowest level they could maintain long term. | Reduced intake of carbohydrates to 20g/day to achieve lowest level of carbohydrates during first 8 weeks; in the second stage slowly add carbohydrates in increments of 5 g/d and hold for 1–4 weeks before adding another 5 g/day; third stage to identify lowest level they could maintain long term. | 6 |
| Gardner, 2018 [43] | 632 | USA | Reduced intake of fat to 20 g/day during first 8 weeks; slowly add carbohydrates in increments of 5–15 g/d per week until they reached lowest level of intake they could maintain indefinitely | Reduced intake of carbohydrates to 20 g/day during first 8 weeks; slowly add carbohydrates in increments of 5–15 g/d per week until they reached lowest level of intake they could maintain indefinitely | 12 |
| Halyburton, 2007 [44] | 121 | Australia | 46% carbohydrate, 30% fat, 245 protein | 4% carbohydrate, 61% fat (20% saturated fat), 35% protein | 1.84 |
| Haufe, 2011 [60] | 174 | Germany | 20% fat, 0.8 g protein/kg body weight, and the remaining energy content provided by carbohydrates in the reduced fat group | 90 g carbohydrates, 0.8 g protein/kg body weight, and a minimum of 30% fat in the reduced carbohydrate group | 6 |
| Jenkins, 2014 [11] | 50 | Canada USA |
High-carbohydrate lacto-ovo vegetarian diet 58% carbohydrate, 25% fat, 16% protein | Low-carbohydrate vegan diet with 265% carbohydrates, 43% fat, 31% vegetable proteins | 6 |
| Keogh, 2007 [44] | 44 | Australia | 60% carbohydrate, 20% fat, 20% protein | 33% carbohydrate, 27% fat, 40% protein | 3 |
| Kirk, 2009 [26] | 22 | USA | ≥180 g carbohydrates, 20% fat, 15% protein | ≤50 g carbohydrates/day, 10% carbohydrates, 75% fat, 15% protein | 2.75 |
| McAuley, 2005 [45] | 96 | New Zealand | High-carbohydrate, high-fibre diet (control group) based on that recommended by Diabetes and Nutrition Study Group (DNSG) of the European Association for the Study of Diabetes (EASD) and the diet was implemented using the national healthy eating guidelines, with slight modifications | Atkins, in first 2 weeks <20 g/day of carbohydrates; during weeks 3 to 8 of the weight loss phase, carbohydrate was reintroduced by the addition of 5 g/day each week, so that a maximum of 50 g of carbohydrate per day was consumed by week 8. | 3.68 |
| McLaughlin, 2006 [46] | 65 | USA | 16 week calorie restriction 60% carbohydrates, 25% fat, 15% protein Then 2 week weight maintenance with eucaloric diet based on weight and macronutrient content similar to hypocaloric diet |
16 week calorie restriction 40% carbohydrates, 45% fat, 15% protein Then 2 week weight maintenance with eucaloric diet based on weight and macronutrient content similar to hypocaloric diet |
4.14 |
| Meckling, 2004 [47] | 40 | Canada | Low fat diet, eliminated high-fat dairy products and substitute with no-fat or low fat alternatives. | The goal of the low carbohydrate diet was to restrict carbohydrates to 50–70 g/d by gradually restricting carbohydrate intake from 100 g on d 0 to 50–70 g by d 5. | 2.3 |
| Nickols-Richardson, 2005 [48] | 28 | USA | 60% carbohydrate, 25% fat, 15% protein | Atkins Nutritional Approach: during the first 2 weeks, consumed <20 g carbohydrate/day; thereafter, they increased their carbohydrate intake by 5 g/week to 40 g carbohydrate/day at week 6. | 1.38 |
| Phillips, 2008 [49] | 28 | USA | 30% fat modelled after an American Heart Association diet | Atkins-style diet with 20 g/day carbohydrates supplemented with protein and fat content according to the Atkins’ diet recommendations | 1.38 |
| Ruth, 2013 [27] | 55 | USA | 60% complex carbohydrates, 25% fat, 15% protein | ≤40 g/day carbohydrates, 60% fat, 15% protein | 12 |
| Sacks, 2009 [7] | 811 | USA | Low Fat High Protein 55% carbohydrate, 20% fat, 25% protein Low Fat Average Protein 65% carbohydrate, 205 fat, 15% protein |
High fat high protein 35% carbohydrate, 20% fat, 15% protein (High fat average protein group did not meet criteria) |
24 |
| Samaha, 2003 [50] | 132 | USA | Received instruction in accordance with the obesity-management guidelines of the National Heart, Lung, and Blood Institute, including caloric restriction to create a deficit of 500 calories/day, with ≤30% of total calories derived from fat. | ≤30 g/day carbohydrates, no instruction on reducing total fat intake | 6 |
| Sharman, 2004 [51] * | 15 | USA | ~55% carbohydrate, 25% fat, 20% protein | 10% carbohydrates, 60% fat, 30% protein | 1.5 |
| Soenen, 2012 [52] | 139 | The Netherlands | High protein normal carbohydrate 50% carbohydrate, 30% fat, 20% protein (Additionally had a normal protein normal carbohydrate group that did not match selection criteria) |
(1) High protein low carbohydrate 25% carbohydrate, 55% fat, 20% protein (2) Normal protein low carbohydrate 25% carbohydrate, 65% fat, 10% protein |
12 |
| Stern, 2004 [53] | 132 | USA | Reduced caloric intake by 500 calories per day, with less than 30% of calories derived from fat | <30 g/day carbohydrate | 12 |
| Varady, 2011 [54] | 20 | USA | 55% carbohydrate, 25% fat, 20% protein | 5% carbohydrate, 60% fat, 35% protein | 1.5 |
| Veum, 2017 [55] | 46 | Norway | 53% carbohydrate, 30% fat, 17% protein | 10% carbohydrate, 73% fat, 17% protein | 3 |
| Volek, 2003 [56] * | 10 | USA | Subjects consumed each diet for 4 weeks followed by a 4-week break before crossing over to the other diet. 55% carbohydrate, 25% protein, 20% fat |
Subjects consumed each diet for 4 weeks followed by a 4-week break before crossing over to the other diet. 10% carbohydrate, 60% fat, 30% protein |
1 |
| Volek, 2004 [57] * | 13 | USA | 55% carbohydrate, 25% protein, 20% fat | 10% carbohydrate, 60% fat, 30% protein | 1 |
| Wal, 2007 [58] | 125 | USA | Moderate carbohydrate group | The Low carbohydrate group | 3 |
| Wood, 2012 [59] | 42 | USA | <30% fat with <10% saturated fat and <300mg/day dietary cholesterol | <50 g of carbohydrate per day, with no specific restrictions provided with respect to total or saturated fat consumption or dietary cholesterol consumption. | 3 |
* Crossover studies.