Relationship Between Weekly Patterns of Caloric Intake and Reported Weight Loss Outcomes: Retrospective Cohort Study.

BACKGROUND: Although millions of overweight and obese adults use mobile phone apps for weight loss, little is known about the predictors of success. OBJECTIVE: The objective of this study was to understand the relationship between weight loss outcomes and weekly patterns of caloric intake among overweight and obese adults using a mobile phone app for weight loss. METHODS: We examined the relationship between weekly patterns of caloric intake and weight loss outcomes among adults who began using a weight loss app in January 2016 and continued consistent use for at least 5 months (N=7007). Unadjusted and adjusted linear regression analyses were used to evaluate the predictors of percentage of bodyweight lost for women and men separately, including age, body mass index category, weight loss plan, and difference in daily calories consumed on weekend days (Saturday and Sunday) versus Monday. RESULTS: In adjusted linear regression, percentage of bodyweight lost was significantly associated with age (for women), body mass index (for men), weight loss plan, and differences in daily caloric intake on Mondays versus weekend days. Compared with women consuming at least 500 calories more on weekend days than on Mondays, those who consumed 50 to 250 calories more on weekend days or those with balanced consumption (±50 calories) lost 1.64% more and 1.82% more bodyweight, respectively. Women consuming 250 to 500 calories or more than 500 calories more on Mondays than on weekend days lost 1.35% more and 3.58% more bodyweight, respectively. Compared with men consuming at least 500 calories more on weekend days than on Mondays, those consuming 250 to 500 calories or more than 500 calories more on Mondays than on weekend days lost 2.27% and 3.42% less bodyweight, respectively. CONCLUSIONS: Consistent caloric intake on weekend days and Mondays or consuming slightly fewer calories per day on Mondays versus weekend days was associated with more successful weight loss. TRIAL REGISTRATION: ClinicalTrials.gov NCT03136692; https://clinicaltrials.gov/ct2/show/NCT03136692 (Archived by WebCite at http://www.webcitation.org/6y9JvHya4).

Experience-dependent effects of context and restraint stress on corticolimbic c-Fos expression.

Stressors are typically multidimensional, comprised of multiple physical and sensory components that rarely occur as single isolated events. This study used a 2-day stress exposure paradigm to assess functional activation patterns (by Fos expression) in key corticolimbic structures following repeated context, repeated restraint, context followed by restraint or restraint followed by context. On day 1, rats were transported to a novel context and either restrained for 6 h or left undisturbed. On day 2, these two groups were either restrained or not in the same context, then processed for Fos immunohistochemistry. Regardless of prior stress experience, rats exposed to context only on day 2 expressed more Fos-like immunoreactive (IR) labeling in CA1 and CA3 of dorsal hippocampus, basolateral amygdala and central amygdala than those that were not. This pattern was reversed in the dentate gyrus infrapyramidal blade. In contrast, in the infralimbic region of the medial prefrontal cortex (mPFC), the experience of a single restraint on either day 1 or day 2 rats elevated Fos-like IR relative to rats that had been exposed to context alone. These data show that exposure to context produces robust Fos induction in the hippocampus and amygdala, regardless of prior experience with restraint and compared to the immediate experience of restraint, with prior experience modulating Fos expression within the mPFC.

Environmental enrichment protects against the effects of chronic stress on cognitive and morphological measures of hippocampal integrity.

Chronic stress has detrimental effects on hippocampal integrity, while environmental enrichment (EE) has beneficial effects when initiated early in development. In this study, we investigated whether EE initiated in adulthood would mitigate chronic stress effects on cognitive function and hippocampal neuronal architecture, when EE started one week before chronic stress began, or two weeks after chronic stress onset. Adult male Sprague Dawley rats were chronically restrained (6h/d) or assigned as non-stressed controls and subdivided into EE or non-EE housing. After restraint ended, rats were tested on a radial arm water maze (RAWM) for 2-d to assess spatial learning and memory. The first study showed that when EE began prior to 3-weeks of chronic stress, EE attenuated chronic stress-induced impairments in acquisition, which corresponded with the prevention of chronic stress-induced reductions in CA3 apical dendritic length. A second study showed that when EE began 2-weeks after the onset of a 5-week stress regimen, EE blocked chronic stress-induced impairments in acquisition and retention at 1-h and 24-h delays. RAWM performance corresponded with CA3 apical dendritic complexity. Moreover, rats in EE housing (control or stress) exhibited similar corticosterone profiles across weeks, which differed from the muted corticosterone response to restraint by the chronically stressed pair-housed rats. These data support the interpretation that chronic stress and EE may act on similar mechanisms within the hippocampus, and that manipulation of these factors may yield new directions for optimizing brain integrity and resilience under chronic stress or stress related neuropsychological disorders in the adult.