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Effects of Plant-Based Diets on Weight Status: A Systematic Review.
Tran, E, Dale, HF, Jensen, C, Lied, GA
Diabetes, metabolic syndrome and obesity : targets and therapy. 2020;13:3433-3448
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Being overweight or obese is a huge risk factor for many detrimental conditions. It is estimated that around one-third of the world’s population will be overweight or obese by 2025. Hence there is a need to look at dietary strategies in the prevention and treatment of overweight and obesity. Plant-based diets have always existed, however interest in the topic has increased recently and more research is being done on the health-related effects of different plant-based diets. There are many reasons why someone might convert to a plant-based diet, possible health benefits such as weight management are among the most common. The purpose of this review was to evaluate intervention studies assessing the effects of different plant-based diets on body mass index and weight. The results suggest that plant-based diets may improve weight status in some patient groups. It should be noted that only one study out of the 19 included in the review had normal weight, clinically healthy participants. The study populations for the rest were overweight, obese or had type 2 diabetes. Future research should aim to include a representative study population and apply study diets without dietary restrictions.
Abstract
There is an increasing number of people who convert to a plant-based diet. The desire for health benefits, including weight management, is often a contributing factor behind this dietary choice. The purpose of this review was to evaluate intervention studies assessing the effects of different plant-based diets on body mass index and weight. A literature search was conducted in PubMed until December 2019. Twenty-two publications from 19 studies were included. The majority of them were randomized controlled trials comparing a low-fat vegan diet to an omnivore diet in participants with overweight, type 2 diabetes mellitus and/or cardiovascular disease. All studies reported weight reductions, of which seven revealed significant differences, and four revealed non-significant differences between the intervention and the control groups. The results suggest that plant-based diets may improve weight status in some patient groups. Due to restrictions in fat intake in many studies, followed by reduced energy intake, the effects of the different interventions differ depending on the specific plant-based diets investigated. Future research should aim to include a representative study population and apply study diets without dietary restrictions.
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Effect of Weight Loss after Bariatric Surgery on Thyroid-Stimulating Hormone Levels in Euthyroid Patients with Morbid Obesity.
Juiz-Valiña, P, Outeiriño-Blanco, E, Pértega, S, Varela-Rodriguez, BM, García-Brao, MJ, Mena, E, Pena-Bello, L, Cordido, M, Sangiao-Alvarellos, S, Cordido, F
Nutrients. 2019;11(5)
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Obesity is associated with many health issues, including thyroid problems. The aim of this observational study was to investigate the effect of weight loss surgery on thyroid hormones. 129 morbidly obese people with normal thyroid function were included in the study. 12 months after weight loss surgery, the levels of thyroid stimulating hormone (TSH) had significantly decreased from 3.3 to 2.1 µU/mL. Levels of the thyroid hormone free thyroxine (T4) also significantly decreased from 1.47 to 1.12 ng/dL. Those that lost more weight following surgery tended to have a greater reduction in TSH. Fasting blood glucose also significantly improved after surgery. The authors concluded that obesity is associated with raised TSH levels, and this makes diagnosing thyroid problems in people with morbid obesity more complicated.
Abstract
Obesity is associated with several endocrine abnormalities, including thyroid dysfunction. The objective of this study was to investigate the effect of weight loss after bariatric surgery on thyroid-stimulating hormone (TSH) levels in euthyroid patients with morbid obesity. We performed an observational study, evaluating patients with morbid obesity submitted to bariatric surgery. We included 129 patients (92 women) and 31 controls (21 women). Clinical, anthropometric, biochemical, and hormonal parameters were evaluated. The primary endpoint was circulating TSH (µU/mL). Fasting TSH levels were higher in the obese group (3.3 ± 0.2) than in the control group (2.1 ± 0.2). The mean excessive body mass index (BMI) loss (EBMIL) 12 months after bariatric surgery was 72.7 ± 2.1%. TSH levels significantly decreased in the obese patients after surgery; 3.3 ± 0.2 vs. 2.1 ± 0.2 before and 12 months after surgery, respectively. Free thyroxine (T4) (ng/dL) levels significantly decreased in the obese patients after surgery; 1.47 ± 0.02 vs. 1.12 ± 0.02 before and 12 months after surgery, respectively. TSH decreased significantly over time, and the decrement was associated with the EBMIL. In euthyroid patients with morbid obesity, weight loss induced by bariatric surgery promotes a significant decline of the increased TSH levels. This decrement of TSH is progressive over time after surgery and significantly associated with excess BMI loss.
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Acceptability of a very-low-energy diet in Type 2 diabetes: patient experiences and behaviour regulation.
Rehackova, L, Araújo-Soares, V, Adamson, AJ, Steven, S, Taylor, R, Sniehotta, FF
Diabetic medicine : a journal of the British Diabetic Association. 2017;34(11):1554-1567
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Patients with type 2 diabetes can return to normal blood glucose levels through substantial weight loss. While many studies have addressed this, very few have assessed the effects of adherence to a very-low-energy diet (VLED) on patients’ quality of life. The aim of this study was to evaluate the experiences of adhering to VLED for patients in remission for type 2 diabetes. Fifteen participants were interviewed before and after the 8-week VLED intervention and narratives were analysed. This study identified common barriers, facilitators and strategies used by the participants. Overall, participants found adherence easier than anticipated, and found barriers to be offset by suggested behaviour-regulation strategies. Based on this study, the authors conclude dietary treatment for reversal of type 2 diabetes is acceptable and feasible in motivated patients, and suggest further controlled research be done to confirm the validity and applicability of these findings.
Abstract
AIMS: To evaluate the acceptability of an 8-week very-low-energy diet for remission of Type 2 diabetes, and to identify barriers and facilitators of adherence and behaviour-regulation strategies used by participants in the Counterbalance study. METHODS Eighteen of 30 participants in the Counterbalance study (ISRCTN88634530) took part in semi-structured interviews. Of these, 15 participants were interviewed before and after the 8-week very-low-energy diet intervention. Thematic analysis was used to analyse the narratives. RESULTS The prospect of diabetes remission, considerable weight loss, and long-term health improvement provided participants with substantial initial motivation. This motivation was sustained through the experience of rapid weight loss, improvements in blood glucose levels, social support and increased physical and psychological well-being. Overall, adherence to the very-low-energy diet for 8 weeks was perceived as much easier than anticipated, but required personal effort. Participants addressed challenges by removing food from the environment, planning, avoidance of tempting situations or places, and self-distraction. Weight loss and improvements in blood glucose levels lead to a sense of achievement and improvements in physical and psychological wellbeing. CONCLUSIONS Dietary treatment for reversal of Type 2 diabetes is acceptable and feasible in motivated participants, and the process is perceived as highly gratifying. Research outside of controlled trial settings is needed to gauge the generalisability of these findings.