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Seasonality is a phenomenon that is characterized by changes over the year in sleep, mood, behaviour, appetite and body weight. In humans, seasonal variations have been found in certain variables, such as lipid variables and body mass index. We hypothesize that this rhythm could influence the expected variation of the levels of biochemical variables in cases of body weight loss. Thus, the goal of this study was to observe whether the time of year in which bariatric surgery (BS) took place modulated the changes in several variables related to glucidic and lipid metabolism. Blood samples were obtained from 24 women and 10 men before BS and 1 and 3 months after BS. We calculated the percentage of variation that occurred for each individual and for each variable as a function of the time of the year. Data were adjusted to a 12-month period sinusoidal curve, with significance being set at p < 0.05. The results showed that almost all of the studied variables changed due to the BS according to a seasonal rhythm. Most of the variables showed a decrease that was most prominent in winter. In the cases of body mass index (BMI), adrenocorticotropin hormone (ACTH), and cortisol, the highest variation occurred in winter. Insulin and cholesterol in high-density lipoproteins (cHLD) variations were higher in springtime. Glucose variation showed a decrease after surgery with acrophase in summer-fall and plasminogen activator inhibitor-1 (PAI-1) and homeostatic model assessment-insulin resistance (HOMA-IR) in spring-summer. Ghrelin levels showed increases with a rhythm of variation with an acrophase in summer-fall. The seasonal rhythm found in this study fits nearly with the inverse of the endogenous circannual rhythm of the variables studied. The time of the year when the highest variation takes place is related to the circannual rhythm of the variable. The results agree with the manifestation of seasonal rhythm in human biochemical variables, which are reflected in the responses to weight loss after BS.

Seasonal variations have been described in humans in several variables such as sleep, mood, appetite, food preferences, or body weight. We hypothesized that these variations could also influence the decrease in body weight rate in patients submitted to body weight loss interventions. Thus, here we tested the variations of weight loss according to the time of the year the surgery took place in a group patients (n = 1322) submitted to bariatric surgery in the Hospital Universitari de la Vall d'Hebron in Barcelona (geographical coordinates: 41°25ʹ41″N 2°8ʹ32″E). For the analysis, the percentage of total body weight loss (%TWL), excess body weight loss (%EWL) and percentage of body mass index loss (%BMIL) were calculated at 3 (n = 1255), 6 (n = 1172), 9 (n = 1002), and 12 months (n = 1076) after surgery. For %EWL and %BMIL a statistically significant seasonal variation was detected when the variables were calculated at 3 months, but not at the other times, with more weight loss in summer-fall. However, seasonal variations were not detected for %TWL (p = 0.09). The mean amplitude of the seasonal rhythm for %EWL was of 1.8%, while for the rhythm of %BMIL was 0.7%. Moreover, a second peak was detected in January-February modulating the seasonal rhythm of the two variables. Results confirm seasonal variations in humans and indicate that short term responses to weight loss can be modulated by the time of year. [ABSTRACT FROM AUTHOR]

Background & aims: We have investigated the differences in plasma parameters and serum trace elements between "healthy" and unhealthy morbidly obese patients before and after Roux-en-Y gastric bypass surgery. Methods: A group of 32 morbidly obese patients undergoing bariatric surgery were divided into three groups. Group 1 subjects were free of dyslipidemia and type II diabetes mellitus (defined as "healthy" obese, DM-DL-); Group 2 subjects had only the presence of dyslipidemia (DM-DL+), while group 3 patients demonstrated the presence of both (DM + DL+). In all patients, we studied haematological, haemostasis, anaemia, coagulation plasma and trace elements parameters before and 1, 6 and 12 months after gastric bypass surgery. Results: We found significant differences in some haematological parameters, including haemostasis (e.g., T-Quick, p = 0.0048) and coagulation (e.g., ATIII and PAI-1, p = 0.001 and p < 0.0001, respectively) and in anaemia parameters (e.g., folate, cobalamin and transferrin, p = 0.0002, p < 0.0001 and p = 0.0001, respectively) but also in serum trace elements between the groups. However, the response to bariatric surgery was similar in the three groups. Conclusion: Any healthy morbid obese subject is really metabolically "unhealthy" because he or she has many other haematologic or serum abnormalities that are often not included in the criteria for the definition of "healthy" in these obese subjects. [ABSTRACT FROM AUTHOR]