TABLE 2.
Effects of Test diets varying in carbohydrate content on estimated energy requirement during weight-loss maintenance in the Framingham State Food Study1
| EER by diet group, kcal/d | Linear trend, kcal/d | |||||
|---|---|---|---|---|---|---|
| Analysis | Low-Carb | Moderate-Carb | High-Carb | P 2 | (Low-Carb) – (High-Carb) | P 3 |
| Baseline (START) 4 | ||||||
| ITT | 2284 (2214, 2354) | 2276 (2202, 2350) | 2229 (2152, 2305) | 0.54 | 56 (−50, 161) | 0.30 |
| PP | 2330 (2247, 2413) | 2309 (2219, 2398) | 2277 (2175, 2378) | 0.73 | 53 (−80, 187) | 0.43 |
| Diet effect, model 1 4 | ||||||
| ITT | 2517 (2396, 2639) | 2437 (2308, 2565) | 2303 (2170, 2435) | 0.07 | 215 (32, 398) | 0.02 |
| PP | 2565 (2432, 2698) | 2447 (2304, 2591) | 2289 (2127, 2452) | 0.04 | 276 (61, 490) | 0.01 |
| Diet effect, model 2 (model 1 additionally adjusted for START EER) 5 | ||||||
| ITT | 2505 (2391, 2620) | 2429 (2308, 2550) | 2324 (2199, 2450) | 0.12 | 181 (8, 353) | 0.04 |
| PP | 2552 (2427, 2677) | 2447 (2312, 2581) | 2308 (2155, 2460) | 0.06 | 245 (43, 446) | 0.02 |
| Diet effect, model 3 (model 2 excluding participant with hypothyroidism) 6 | ||||||
| ITT | 2528 (2414, 2642) | 2432 (2312, 2551) | 2323 (2200, 2447) | 0.07 | 204 (33, 376) | 0.02 |
| PP | 2582 (2458, 2706) | 2448 (2316, 2579) | 2309 (2160, 2458) | 0.03 | 272 (74, 471) | 0.008 |
| Diet effect, model 4 (model 3 without adjustment for the polytomous cohort variable) 7 | ||||||
| ITT | 2533 (2411, 2656) | 2460 (2333, 2587) | 2288 (2156, 2419) | 0.03 | 246 (64, 427) | 0.009 |
| PP | 2594 (2465, 2723) | 2467 (2331, 2602) | 2271 (2120, 2422) | 0.008 | 323 (122, 525) | 0.002 |
Values are means (95% CI). Data were calculated per kg and normalized to average weight of 82 kg at START. EER, estimated energy requirement; ITT, intention-to-treat analysis; PP, per protocol analysis; PRE, preweight loss; START, start of randomized trial (postweight loss, prerandomization); TEE, total energy expenditure measured using DLW methodology.
P value is for the overall diet group effect.
P value for (Low-Carb) – (High-Carb) contrast is equivalent to a test for linear trend across diet groups (with equal, 20% increments in the contribution of carbohydrate to total energy intake from Low-Carb to Moderate-Carb and from Moderate-Carb to High-Carb.)
N = 147 (ITT), N = 110 (PP). Covariates included cohort, sex, age, Run-in weight loss (% PRE body weight), START TEE, and START body weight. One participant (ITT only) had unusable START TEE data.
N = 147 (ITT), N = 110 (PP). Covariates included cohort, sex, age, Run-in weight loss (% PRE body weight), START TEE, START body weight, and START EER. One participant (ITT only) had unusable START TEE data.
N = 146 (ITT), N = 109 (PP). One participant (ITT and PP) developed hypothyroidism and was an a priori exclusion from analyses of the primary outcome (8, 11). Covariates included cohort, sex, age, Run-in weight loss (% PRE body weight), START TEE, START body weight, and START EER. One participant had unusable START TEE data (ITT only).
N = 146 (ITT), N = 109 (PP). One participant (ITT and PP) developed hypothyroidism and was an a priori exclusion from analyses of the primary outcome (8, 11). Covariates included sex, age, Run-in weight loss (% PRE body weight), START TEE, START body weight, and START EER. One participant (ITT only) had unusable START TEE data. Elimination of the polytomous cohort variable decreased predictor Df by 10 in ITT, and 9 in PP (because there were no participants in the PP analysis for 1 of the 11 categories of this variable).
DLW, doubly labeled water.