TABLE 2.
Summary of study design and population characteristics of included intervention studies in updated, original, and combined data sets1
| Studies published from 2013 to 2016 (n = 97) | Original evidence map (n = 201) | Combined (n = 298) | |
|---|---|---|---|
| Design, n (%) | |||
| Randomized (parallel) | 27 (28) | 45 (22) | 72 (24) |
| Randomized (crossover) | 58 (60) | 91 (45) | 149 (50) |
| Nonrandomized (with control) | 3 (3) | 29 (14) | 32 (11) |
| Single-arm | 7 (7) | 25 (12) | 32 (11) |
| Other2 | 2 (2) | 11 (5) | 13 (4) |
| Study duration, n (%) | |||
| <1 d | 41 (43) | 84 (42) | 125 (42) |
| 1–14 d | 24 (25) | 45 (23) | 69 (23) |
| 15 d to 1 mo | 14 (14) | 26 (13) | 40 (13) |
| >1 to 6 mo | 16 (16) | 41 (20) | 57 (19) |
| >6 mo to 1 y | 1 (1) | 2 (1) | 3 (1) |
| >1 to 2 y | 1 (1) | 10 (5) | 14 (5) |
| >2 y | 0 (0) | 1 (1) | 1 (0.3) |
| Sample size, n | 22 (6–465) | 18 (5–2026) | 19 (5–2026) |
| Published power calculation, n (%) | 32 (33) | 24 (12) | 56 (19) |
| Age,3 y | 29.8 (1.5–77.7) | 35.4 (5–72) | 33.7 (1.5–77.7) |
| Study population, n (%) | |||
| Adults | 75 (77) | 180 (90) | 255 (86) |
| Children | 12 (12) | 11 (5) | 23 (8) |
| Adolescents | 8 (8) | 3 (1) | 11 (4) |
| Mixed | 0 (0) | 7 (3) | 7 (2) |
| Baseline health status, n (%) | |||
| Healthy | 47 (48) | 108 (54) | 155 (52) |
| Overweight/obese | 19 (20) | 18 (9) | 37 (12) |
| Diabetes | 4 (4) | 42 (21) | 46 (15) |
| Mixed healthy and nonhealthy | 1 (1) | 16 (8) | 17 (6) |
| Other | 12 (12) | 16 (8) | 28 (9) |
| Not specified | 14 (14) | 1 (1) | 15 (5) |
| Funding source, n (%) | |||
| Government | 26 (27) | 39 (19) | 65 (22) |
| Industry | 23 (24) | 24 (12) | 47 (16) |
| Nonprofit | 21 (22) | 31 (15) | 52 (17) |
| Government and industry | 5 (5) | 23 (11%) | 28 (9) |
| Government and nonprofit | 7 (7) | 24 (12) | 31 (10) |
| Nonprofit and industry | 1 (1) | 6 (3) | 7 (2) |
| Government, industry, and nonprofit | 0 (0) | 8 (4) | 8 (3) |
| No data given | 14 (14) | 46 (23) | 60 (20) |
| Outcome categories,4n (%) | |||
| Diabetes risks | 54 (56) | 147 (73) | 201 (67) |
| Cardiovascular disease risks | 38 (39) | 109 (54) | 147 (49) |
| Body weight | 22 (23) | 52 (26) | 74 (25) |
| Body composition | 19 (20) | 18 (9) | 37 (12) |
| Appetite | 28 (29) | 31 (15) | 59 (20) |
| Dietary intake | 13 (13) | 32 (16) | 45 (15) |
| Liver health | 9 (9) | 15 (7) | 24 (8) |
| Other outcomes | 45 (46) | 111 (55) | 156 (52) |
1
Values are n (%) or means (minimum–maximum). The unit of analysis is 1 study, with the exception of Sample size and Age.
2
Other designs include quasi-experimental design or unclear intervention designs.
3
Fifteen studies did not report mean or median age so were not included in the calculation. Minimum and maximum mean ages are shown in parentheses.
4
Because some studies examined multiple outcomes across multiple categories, percentages sum to >100%.