The purpose of this study was to examine the validity of the 1971-2010 United States Department of Agriculture's (USDA's) loss-adjusted food availability (LAFA) per capita caloric consumption estimates. Estimated total daily energy expenditure (TEE) was calculated for nationally representative samples of US adults, 20-74 years, using the Institute of Medicine's predictive equations with “low-active” (TEE L-ACT) and “sedentary” (TEE SED) physical activity values. TEE estimates were subtracted from LAFA estimates to create disparity values (kcal/d). A validated mathematical model was applied to calculate expected weight change in reference individuals resulting from the disparity. From 1971-2010, the disparity between LAFA and TEE L-ACT varied by 394 kcal/d—(P < 0.001), from −205 kcal/d (95% CI: −214, −196) to +189 kcal/d (95% CI: 168, 209). The disparity between LAFA and TEE SED varied by 412 kcal/d (P < 0.001), from −84 kcal/d (95% CI: −93, −76) to +328 kcal/d (95% CI: 309, 348). Our model suggests that if LAFA estimates were actually consumed, reference individuals would have lost ~1-4 kg/y from 1971-1980 (an accumulated loss of ~12 to ~36 kg), and gained ~3-7 kg/y from 1988-2010 (an accumulated gain of ~42 to ~98 kg). These estimates differed from the actual measured increments of 10 kg and 9 kg in reference men and women, respectively, over the 39-year period. The USDA LAFA data provided inconsistent, divergent estimates of per capita caloric consumption over its 39-year history. The large, variable misestimation suggests that the USDA LAFA per capita caloric intake estimates lack validity and should not be used to inform public policy.