Weight loss
Health
Fat accumulation in the liver (not related to alcohol, viral infection or liver diseases) is associated with obesity, insulin resistance, diabetes and alteration of lipid profiles, oxidative stress, mitochondrial dysfunction and inflammation.[1] Weight loss significantly improves fasting flow-mediated vasodilation of the brachial artery in adults (a measurement of endothelial function).[2] A meta-analysis of 20 studies involving 1259 participants indicated that weightloss (mean 8% of initial bodyweight) improves pulse wave velocity (a measure of arterial stiffness).[3]
Though exercise increases insulin sensitivity (preventing insulin resistance)[4], calorie restriction does the same, through autophagy.[5][6] This is regardless of whether this restricted diet is moderate-carbohydrate (40-45% of energy) and increased-protein (25-30%), or high-carbohydrate diet (55-60%) and moderate-protein (15%).[7] A low-calorie diet significantly improves the HRR (Heart Rate Recovery) after maximum exercise, predicting cardiovascular disease risk and mortality.[8] Menstrual disturbances are associated with energy deficits over 470 kcal / day.[9]
Gender
A systematic review of 49 high-quality scientific studies shows that there is little evidence to indicate that men and women should adopt different weight loss strategies.[10]
Nursing
Intensive nursing strategies for increasing self-efficacy for weight control and health-promoting behaviour may be essential components for better weight loss in the initial stage of a weight management intervention. Particularly increases in diet self-efficacy had a significant indirect effect on initial weight loss.[11] Individuals vary in their responsivity to cues that motivate overeating. Those higher in responsivity need specialized self-regulatory skills. These skills include an ability to tolerate uncomfortable internal reactions to triggers and a reduction of pleasure, behavioral commitment to clearly-defined values, and metacognitive awareness of decision-making processes. Such acceptance-based interventions based on these skills have so far proven efficacious for weight control, especially for those who are the most susceptible to eating in response to internal and external cues.[12] Step counts may be key area to target.[13] Successfully achieving the target weight loss in a comprehensive program predicts subsequent maintenance of lower weight without increasing the risk of dropout.[14] Providing the additional strategies at predetermined times over the intervention period enhances weight loss.[15]
Calorie restriction
Adherence to any diet may result in weight loss, regardless of whether low in carbohydrates or low in fat.[16] The analysis of 119 scientific publications in participation with ten medical specialty societies resulted in the recommendation that for the purpose of weightloss and stabilization of a lower weight, a diet with an energy deficit of 500 kcal/day and a low energy density should be instituted.[17] Alternate-day fasting (25% energy intake alternated with ad libitum) diet decreases body weight, BMI and fat mass, regardless of whether the diet is high (40%) or moderately low in fat (25%).[18] Negative-calorie diets ("containing less energy than required for its digestion") and low-calorie diets are equally efficacious regarding weightloss.[19] Very-low-energy diets and ketogenic low-carbohydrate diets are associated with a suppression of appetite, despite weightloss.[20]
Weightloss and Exercise
Aerobic exercise training in women typically results in minimal fat loss / reductions in bodyweight.[21] Exercise interventions (55-64%) more than than diet interventions (12-44%) tend to trigger behavioral compensation (resulting in less weight loss).[22] A quantitative analysis of the 21 scientific trials, including 3,521 participants), revealed that comparing exercise versus diet, diet resulted in a significantly more pronounced decrease in body weight. Diet plus exercise, in comparison to diet alone, reduced total fat, but did not result in a reduction in waist circumference. [23] As compared to diet restriction alone (energy content based on 70% of measured resting metabolic rate), the addition of strength or aerobic training does not improve changes in BMI, body fat or metabolic risk factors.[24] Dietary restriction with and without exercise result in similar weight loss and no signficant changes in the resting metabolic rate.[25] If not followed up by exercise, low-calorie-induced weight loss will result in a decrease in total energy expenditure and non-training physical activity energy expenditure. (less weight to carry around) Resting energy expenditure will decrease regardless of whether weight loss is follwed up by aerobic or resistance exercise, or not. [26] The latter may be due to an increase in autophagy. Low physical activity protects lean body mass.[27] Performing aerobic exercise after an overnight fast does not accelerate the loss of body fat, compared to non-fasted exerrcise.[28]
Compared to food restriction alone, the addition of running wheel activity makes mice loose weight faster, but also prevents further weight loss beyond a crucial point of body weight loss (especially fat mass). Both restricted groups adapted their energy metabolism differentially in the short and long term, with less fat oxidation and a preferential use of glucose in the mice that were also submitted to running wheel activity.[29]
