Are You Underestimating Your Calorie Intake?
Whether you are on a structured eating plan or just doing your best to eat healthy, it is extremely beneficial to have a good idea of how many calories you are consuming on a daily basis. Odds are that unless you are paying for a meal plan or you have a scale out and are preparing all of your own meals, there is going to be some sort of guesswork involved with figuring out just how many calories you are taking in on a daily basis. Unfortunately, we are not nearly as good at making caloric estimations as we tend to think we are.
Here’s what the science suggests:
Discrepancy between self-reported and actual caloric intake and exercise in obese subjects.
Lichtman SW1, Pisarska K, Berman ER, Pestone M, Dowling H, Offenbacher E, Weisel H, Heshka S, Matthews DE, Heymsfield SB.
Some obese subjects repeatedly fail to lose weight even though they report restricting their caloric intake to less than 1200 kcal per day. We studied two explanations for this apparent resistance to diet--low total energy expenditure and underreporting of caloric intake--in 224 consecutive obese subjects presenting for treatment. Group 1 consisted of nine women and one man with a history of diet resistance in whom we evaluated total energy expenditure and its main thermogenic components and actual energy intake for 14 days by indirect calorimetry and analysis of body composition. Group 2, subgroups of which served as controls in the various evaluations, consisted of 67 women and 13 men with no history of diet resistance.
RESULTS:
Total energy expenditure and resting metabolic rate in the subjects with diet resistance (group 1) were within 5 percent of the predicted values for body composition, and there was no significant difference between groups 1 and 2 in the thermic effects of food and exercise. Low energy expenditure was thus excluded as a mechanism of self-reported diet resistance. In contrast, the subjects in group 1 underreported their actual food intake by an average (+/- SD) of 47 +/- 16 percent and overreported their physical activity by 51 +/- 75 percent. Although the subjects in group 1 had no distinct psychopathologic characteristics, they perceived a genetic cause for their obesity, used thyroid medication at a high frequency, and described their eating behavior as relatively normal (all P < 0.05 as compared with group 2).
CONCLUSIONS:
The failure of some obese subjects to lose weight while eating a diet they report as low in calories is due to an energy intake substantially higher than reported and an overestimation of physical activity, not to an abnormality in thermogenesis.
N Engl J Med. 1992 Dec 31;327(27):1893-8.
https://www.ncbi.nlm.nih.gov/pubmed/1454084
This does not necessarily mean that you are destined to be terrible at estimating calories consumed and energy expended, but it is something to keep in mind if you are not necessarily getting all of the results that you had hoped for when you started your fitness journey.