The rate of CO 2 production was calculated using the equations of Schoeller et al. The 2H abundances were measured on a Finnigan H/D device, which allows for high throughput and excellent precision ( 19). The 18O isotope abundances were measured on a Finnigan MAT DeltaS Dual Inlet Gas Isotope Ratio Mass Spectrometer with a CO 2-water equilibration device ( 18). Postdose urine specimens were collected at +4.5 hours and +6 hours on day 1 and days 7, 13, and 14. Two urine specimens were collected and discarded +1.5 hours and +3 hours postdose. The dose was given early in the morning after an overnight fast and collection of two baseline urine specimens. Subjects were given an oral dose (1.0 g/kg body weight) of a mixture that contained 1 part deuterium ( 2H 99.9% enriched) and 19 parts Oxygen-18 ( 18O 10% enriched), followed by 100 mL of tap water used to rinse the dose container. Total daily energy expenditure (TDEE) was measured over a 14-day period using DLW. The aim was to (1) understand the determinants of energy requirements in women with PCOS, including the effects of the reproductive and metabolic hormonal milieu, and (2) compare the energy requirements by DLW analysis with estimates derived from commonly used equations to evaluate their use in women with PCOS. This study reports total daily energy requirements in women with PCOS from a DLW study. In the past decade, the ability of prediction equations to estimate energy requirements has improved because several groups have developed equations from DLW data compiled across studies taking into account all types of energy expended throughout 7- to 14-day periods, including physical activities ( 6). However, DLW studies are not cost-effective or practical for use in clinical settings or large-scale trials therefore, predictive equations that calculate energy requirements on the basis of variables such as age, sex, weight, height, body composition, and physical activity level are available and have been used in women with PCOS ( 5, 15, 16). DLW studies also allow weight stability to be assessed simultaneously ( 14). Given the cost and inefficiencies of caloric titration in clinical settings, DLW is considered the gold standard approach because energy expenditure is assessed over several days while individuals continue their usual behaviors in free-living conditions. These methods rely on the assumption that if body weight is stable throughout the observation period, the energy expenditure must therefore be equivalent to the energy intake, giving rise to the estimated energy requirement for weight stability. Other objective yet indirect methods include doubly labeled water (DLW) and measurement of resting energy expenditure, with indirect calorimetry in combination with measures of physical activity. The only direct method for estimating energy requirements involves caloric titration of food over several days or weeks to achieve energy balance ( 12, 13). If the estimated energy requirement is inaccurate, it can lead to poor weight loss and reduced levels of adherence from patients ( 11). The dietary intake goal prescribed for weight loss is a proportion of the energy requirement and hence should result in a daily energy deficit conducive to weight loss. Research studies suggest that metformin and combinations of oral contraceptive agents are commonly prescribed to alleviate reproductive complaints however, for the overweight and obese patients seeking fertility, a weight loss of 5% to 10% through lifestyle modification is recommended as first-line treatment ( 10). Numerous pharmacological and lifestyle interventions to alleviate these complications and enhance quality of life have been tested ( 7–9).
Diagnostic criteria include irregular menses, androgen excess, and/or polycystic ovaries, with longer-term consequences being hyperinsulinemia and infertility ( 5, 6). Overweight and obesity augment the prevalence of PCOS, and increased adiposity is considered a dominant characteristic in 40% to 60% of cases ( 3, 4).
Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive-aged women ( 1) affecting one in five women worldwide ( 2).
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