Table 1.
Summary of findings for effects of carbohydrate-restricted diets and intermittent fasting in adults with overweight/obesity
| Outcome | Illustrative comparative risk* (95% CI) | No. of participants | Quality of the evidence (GRADE) | ||
|---|---|---|---|---|---|
|
| |||||
| Assumed risk(control) | Corresponding risk | ||||
|
| |||||
| Intervention | Mean difference | ||||
| mLCD† | |||||
| Body weight (kg, follow-up: 8–24 wk) | –3.74 | –4.77 | –1.03 (–1.68 to –0.39) | 3,660 (24 studies) | Low |
| Body mass index (kg/m2, follow-up: 8–24 wk) | –1.5 | –1.73 | –0.23 (–0.46 to 0.00) | 2,750 (15 studies) | Very low |
| Waist circumference (cm, follow-up: 12–24 wk) | –4.83 | –5.48 | –0.65 (–1.16 to –0.14) | 2,340 (15 studies) | Moderate |
| Fat mass (kg, follow-up: 12–24 wk) | –2.92 | –3.36 | –0.44 (–0.83 to –0.04) | 2,080 (14 studies) | Moderate |
| Fat-free mass (kg, follow-up: 12–24 wk) | 0.17 | 0.00 | –0.17 (–0.49 to 0.14) | 1,139 (10 studies) | Low |
| Fat mass (%, follow-up: 12–24 wk) | –2.7 | –2.61 | 0.09 (–0.45 to 0.64) | 445 (4 studies) | Low |
| Systolic blood pressure (mmHg, follow-up: 8–24 wk) | –4.0 | –4.56 | –0.56 (–1.69 to 0.56) | 2,612 (19 studies) | Low |
| Diastolic blood pressure (mmHg, follow-up: 8–24 wk) | –2.5 | –3.19 | –0.69 (–1.39 to 0.01) | 2,615 (19 studies) | Low |
| Triglyceride (mg/dL, follow-up: 8–24 wk) | –11.8 | –25.56 | –13.76 (–19.78 to –7.74) | 2,896 (24 studies) | Low |
| LDL-C (mg/dL, follow-up: 12–24 wk) | –4.6 | –2.31 | 2.29 (–0.41 to 4.99) | 2,721 (21 studies) | Very low |
| HDL-C (mg/dL, follow-up: 8–24 wk) | –0.8 | 1.81 | 2.61 (1.34 to 3.89) | 2,448 (20 studies) | Moderate |
| HbA1c (%, follow-up: 8–24 wk) | –0.2 | –0.40 | –0.20 (–0.39 to –0.01) | 739 (8 studies) | Low |
| Fasting insulin (μU/mL, follow-up: 12–24 wk) | –0.9 | –1.84 | –0.94 (–1.73 to –0.16) | 1,855 (13 studies) | Moderate |
| Fasting glucose (mg/dL, follow-up: 8–24 wk) | –3.1 | –3.42 | –0.32 (–1.23 to 0.58) | 2,143 (17 studies) | Low |
| C-reactive protein (mg/L, follow-up: 8–24 wk) | –0.1 | –0.44 | –0.34 (–0.67 to –0.01) | 1,391 (11 studies) | Low |
| Adiponectin (μg/mL, follow-up: 8–24 wk) | 0.2 | 0.65 | 0.45 (0.15 to 0.76) | 1,356 (8 studies) | Moderate |
| VLCD‡ | |||||
| Body weight (kg, follow-up: 8–24 wk) | –3.75 | –7.42 | –3.67 (–4.84 to –2.51) | 1,266 (14 studies) | Moderate |
| Body mass index (kg/m2, follow-up: 8–24 wk) | –1.0 | –2.88 | –1.88 (–3.11 to –0.65) | 388 (5 studies) | Moderate |
| Waist circumference (cm, follow-up: 8–24 wk) | –4.7 | –8.81 | –4.11 (–8.70 to 0.49) | 233 (2 studies) | Low |
| Fat mass (kg, follow-up: 8–24 wk) | –4.8 | –7.81 | –3.01 (–6.29 to 0.27) | 168 (3 studies) | Low |
| Fat-free mass (kg, follow-up: 8–24 wk) | –0.3 | –1.35 | –1.05 (–1.75 to –0.35) | 168 (3 studies) | Low |
| Fat mass (%, follow-up: 8–24 wk) | –1.45 | –3.33 | –1.88 (–2.87 to –0.89) | 515 (4 studies) | Moderate |
| Systolic blood pressure (mmHg, follow-up: 8–24 wk) | –3.0 | –4.97 | –1.97 (–3.68 to –0.25) | 506 (9 studies) | Moderate |
| Diastolic blood pressure (mmHg, follow-up: 8–24 wk) | –2.1 | –2.78 | –0.68 (–1.79 to 0.44) | 906 (9 studies) | Low |
| Triglyceride (mg/dL, follow-up: 8–24 wk) | –11.9 | –33.23 | –21.33 (–30.46 to –12.21) | 1,059 (13 studies) | Low |
| LDL-C (mg/dL, follow-up: 8–24 wk) | –5.1 | 2.42 | 7.52 (3.34 to 11.70) | 1,023 (12 studies) | Moderate |
| HDL-C (mg/dL, follow-up: 8–24 wk) | 0.0 | 4.30 | 4.30 (1.79 to 6.82) | 1,058 (13 studies) | Low |
| HbA1c (%, follow-up: 8–24 wk) | –0.15 | –0.42 | –0.27 (–0.50 to –0.03) | 354 (6 studies) | Low |
| Fasting insulin (μU/mL, follow-up: 8–24 wk) | –1.55 | –2.92 | –1.37 (–2.89 to 0.15) | 603 (6 studies) | Low |
| Fasting glucose (mg/dL, follow-up: 8–24 wk) | –2.9 | –3.34 | –0.44 (–2.66 to 1.78) | 730 (9 studies) | Low |
| C-reactive protein (mg/L, follow-up: 8–24 wk) | –0.2 | –0.83 | –0.63 (–1.41 to 0.15) | 371 (5 studies) | Low |
| Adiponectin (μg/mL, follow-up: 8–24 wk) | 0.4 | 1.15 | 0.75 (0.29 to 1.21) | 181 (2 studies) | Low |
| Intermittent fasting§ | |||||
| Body weight (kg, follow-up: 12–24 wk) | –3.62 | –4.84 | –1.22 (–3.49 to 1.05) | 554 (8 studies) | Very low |
| Body mass index (kg/m2, follow-up: 12–24 wk) | –1.46 | –1.95 | –0.49 (–1.13 to 0.14) | 380 (5 studies) | Low |
| Waist circumference (cm, follow-up: 12–24 wk) | –2.28 | –4.23 | –1.95 (–4.09 to 0.2) | 180 (3 studies) | Very low |
| Fat mass (kg, follow-up: 12–24 wk) | –1.1 | –1.46 | –0.36 (–0.87 to 0.16) | 540 (8 studies) | Very low |
| Fat-free mass (kg, follow-up: 12–24 wk) | –3.7 | –4.37 | –0.67 (–1.95 to 0.62) | 540 (8 studies) | Very low |
| Fat mass (%, follow-up: 12–24 wk) | –0.9 | –0.63 | 0.27 (–0.48 to 1.01) | 142 (3 studies) | Very low |
| Systolic blood pressure (mmHg, follow-up: 12–24 wk) | –5.7 | –4.83 | 0.87 (–2.56 to 4.39) | 404 (6 studies) | Very low |
| Diastolic blood pressure (mmHg, follow-up: 12–24 wk) | –3.4 | –3.56 | –0.16 (–2.89 to 2.56) | 404 (6 studies) | Very low |
| Triglyceride (mg/dL, follow-up: 12–24 wk) | –22.0 | –23.51 | –1.51 (–17.06 to 14.04) | 432 (6 studies) | Very low |
| LDL-C (mg/dL, follow-up: 12–24 wk) | –12.48 | –12.72 | –0.24 (–5.08 to 4.59) | 387 (5 studies) | Very low |
| HDL-C (mg/dL, follow-up: 12–24 wk) | 0.0 | –0.17 | –0.17 (–3.27 to 2.89) | 432 (6 studies) | Very low |
| HbA1c (%, follow-up: 12–24 wk) | –0.31 | –0.20 | 0.11 (–0.04 to 0.26) | 173 (3 studies) | Very low |
| Fasting glucose (mg/dL, follow-up: 12–24 wk) | –3.00 | –3.89 | –0.89 (–4.30 to 2.53) | 359 (5 studies) | Low |
| Fasting insulin (μU/mL, follow-up: 12–24 wk) | –2.6 | –3.03 | –0.43 (–1.99 to 1.14) | 314 (4 studies) | Low |
| HOMA-IR (follow-up: 12–24 wk) | –0.94 | –1.16 | –0.22 (–1.48 to 1.05) | 119 (2 studies) | Very low |
GRADE Working Group grades of evidence: High quality (Further research is very unlikely to change our confidence in the estimate of effect); Moderate quality (Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate); Low quality (Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate); Very low quality (We are very uncertain about the estimate).
*The basis for the assumed risk is the mean change of outcomes compared to baseline in the control group across studies, and the corresponding risk (and its 95% CI) is based on the assumed risk in the comparison group; †mLCD for overweight/obesity: Patient or population (patients with overweight/obese), Intervention (mLCD); ‡VLCD for overweight/obese: Patient or population (patients with overweight/obesity), Intervention (VLCD); §Intermittent fasting for overweight/obesity: Patient or population (patients with overweight/obesity), Intervention (intermittent fasting).
CI, confidence interval; GRADE, Grading of Recommendations Assessment, Development and Evaluation; mLCD, moderately-low carbohydrate or low carbohydrate diet; LDL-C, lowdensity lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol; HbA1c, glycosylated hemoglobin; VLCD, very-low carbohydrate diet; HOMA-IR, homeostatic model assessment for insulin resistance.