Not conjecture. Study.
A study in the New England Journal of Medicine illustrated this problem. The study looked at subjects that repeatedly failed to lose weight on self-reported caloric intakes of less than 1200 calories.
Total energy expenditure (TEE) and resting metabolic rate (RMR) of the subjects were measured and found to be within five percent of predicted values, which was dramatically higher than the reported intake values.
Additionally, no significant differences in thermic effects of food (TEF) or exercise energy expenditure between the weight loss resistant or normal obese were observed. Low energy expenditure was, therefore, excluded as a reason for self-reported diet resistance. Why were these subjects resistant to weight loss?
The researchers recorded an underreporting of actual food intake by 47 percent (+/- 16), and an over reporting of physical activity by ~50 percent. Based on this and other available data, a trend emerges: the higher one’s BMI and weight, the greater the degree of underreporting of caloric intake.
If a comparison is made between data of reported caloric intakes and actual energy expenditure as measured by the doubly labeled water method (the most accurate available), an interesting picture emerges (Figure 1).
As the graph illustrates, the difference in reported intake in various studies from actual energy expenditure of typical persons at varying BMIs ranges from ~3 – 6 MJ/d (716-1200 kcal/d). Combine this with the typically lower daily activity levels of the obese and overweight and the shroud of mystery begins to lift. If the caloric intake were actually what had been reported, these subjects would have lost weight at record rates.
But, the subjects were not losing weight, indicating that they were dramatically underreporting calorie intake. They are eating more, gaining weight and reporting less. Why did your client gain weight on a low calorie diet? Because they did not eat a low calorie diet.
Why does their weight stay the same, even with a reduction of their caloric intake and increase their exercise volume?
Because they are not reducing their caloric intake and they may be incorrectly reporting their volume of exercise. If they are accurate in their exercise reporting and are not changing their weight as you add more work, then they are simply eating more to compensate for the additional energy expenditure.
These are the facts. What is the likelihood that fat-loss clients who never seem to change defy the laws of thermodynamics? None.