Reason #1: Cortisol & Stress
When you are stressed, your body releases hormones such as cortisol that turn on essential functions for your survival, such as higher blood pressure and rapid decision-making, while inhibiting non-essential functions, such as immune function, digestion, and protein synthesis. (This is helpful if you need to handle an acute stressor, but it is also the reason why chronic stress restricts your ability to shed that extra weight around your midsection). Cortisol acts by suppressing insulin secretion, inhibiting glucose uptake into your cells, and disrupting insulin-signaling to muscle tissue. That means that chronic stress directly causes insulin resistance, which then leads to weight loss resistance, increased inflammation, dyslipidemia (elevated blood fat and cholesterol levels) and hypertension. Even exercise, when performed in excess, can leave you chronically stressed with elevated cortisol levels and overtraining does not just happen to athletes. You may be in this category if you are not recovering properly due to under-nourishment of your body therefore leading to poor sleep quality.
Reason #2: Sleep Deprivation
Only about 35% of all Americans get the recommended amount of sleep every night – between seven and nine hours – and many get less than six hours. Sleep deprivation has severe effects on the human body and weakens the immune and nervous systems so much that you become vulnerable to diseases and neurodegeneration.
When it comes to fat loss, research has shown that getting between four to five hours of sleep per night causes insulin resistance and high glycemic variability which can lead to diabetes, appetite cravings, and weight gain, in what would otherwise be a healthy population. Scarier yet is that all it takes to cause this type of damage is a single night of partial sleep.
Sleep deprivation is known to raise cortisol levels, reduce glucose tolerance and increase sympathetic nervous system activity. One study found that, in addition to reducing insulin sensitivity and glucose tolerance, sleep deprivation produces a neuroendocrine effect by reducing levels of the satiety-inducing hormone leptin and increasing levels of the hunger-stimulating hormone ghrelin. So not only does sleep deprivation reduce your ability to metabolize glucose, but it also makes you want to consume more sugar and/or vegetable-oil-laden snack food.
Reason #3: Not Moving Enough
The brutal truth is that for most people, sitting for eight hours a day does not expend enough energy to counterbalance breakfast, lunch, dinner, and snacks, despite any exercise performed at the beginning or end of the day. Even in people who exercise, habitual sedentary behavior is associated with metabolic syndrome (MS), increased risk of obesity, type 2 diabetes, cardiovascular disease, and premature mortality. When you are regularly sedentary for extended periods, your blood sugar levels go haywire because a low level of physical activity causes unfavorable changes in insulin-signaling, glucose transport, and lipoprotein lipase, the primary enzyme responsible for breaking down fats.
Research also suggests that the time spent being sedentary and the accompanying insulin resistance are partly independent of the amount of time you spend in moderate/vigorous-intensity physical activity. If you spend the majority of your day sitting down or just standing with your knees locked out, that hour you spent at the gym isn’t doing you any metabolic favors. Sitting and even static standing may even place you at risk for heart issues because a hard workout at the end of the day then becomes an attempt to force blood through “kinked” vessels.
Reference: https://bengreenfieldfitness.com/article/fat-loss-articles/reasons-you-cant-lose-weight/
