Weight loss in obese diabetic and non-diabetic individuals and long-term diabetes outcomes--a systematic review

The aim was to review the evidence for the long-term effects of weight loss on diabetes outcomes in obese people or for those at risk of developing type 2 diabetes. Current evidence is mostly based on short-term studies. This is a systematic review of long-term outcomes of weight loss in studies published between 1966 and 2001. Eleven long-term studies with a follow up of more than 2 years were included. Results show that those with diabetes who lost weight intentionally significantly reduced their mortality risks by 25%. Additionally, weight loss of 9–13 kg was most protective. Patients with the risk of developing diabetes due to either family history of diabetes or impaired glucose tolerance, saw a reduction in this risk. Those with large weight losses achievable with surgical interventions reduced their risk by at least 63%. Metabolic handling of glucose improved in 80% of those already with type 2 diabetes who lost weight. Based on one large study, intentional weight loss in obese patients appears to have a beneficial effect on mortality risk for those with type 2 diabetes. Clearly, further studies are needed to endorse this. The risk of developing diabetes being reduced by weight loss was shown in seven studies. However, the results were from studies with different analytical adjustments and outcome indices, making it difficult to make direct comparisons and should be viewed with caution. More long-term prospective studies need to be conducted with commitment to improving the methodological quality and standardization, in order to accurately assess the long-term effects of weight loss for obese diabetic and non-diabetic individuals.     

Effects of weight loss in overweight/obese individuals and long-term hypertension outcomes: a systematic review

Many studies have assessed short-term effects of weight loss on blood pressure, whereas little attention has been paid to long-term effects. We conducted a systematic review to evaluate the long-term effects of weight loss on hypertension outcome measures in adults using literature published from 1966 to 2001. All prospective studies and trials, performed on participants with body mass index of > or =28 kg/m2 with a follow-up of >2 years and weight changes recorded, were included. The data from these studies were used to model the long-term effects on blood pressure. Previous reviews on shorter-term studies indicate a 1:1 drop in blood pressure (mm Hg) with weight loss (kilograms). Our findings, based on studies with follow-up of > or =2 years, demonstrate blood pressure decreases less than this after weight loss. The surgical intervention studies exhibited huge weight losses with undramatic blood pressures changes. When surgical interventions are excluded, the models suggest that for 10 kg weight loss, decreases of 4.6 mm Hg and 6.0 mm Hg in diastolic and systolic blood pressure, respectively, may be expected, about half of that predicted from the short-term trials. Initial blood pressure, the length of follow-up, medication changes, and physiological restrictions may contribute to this reduced effect in the long-term studies. Extrapolation of short-term blood pressure changes with weight loss to the longer term is potentially misleading. The weight/hypertension relationship is complex and needs well-conducted studies with long-term follow-up to examine the effects of weight loss on hypertension outcomes.     

Intentional weight loss in overweight and obese individuals and cognitive function: a systematic review and meta‐analysis

High adiposity in middle age is associated with higher dementia risk. The association between weight loss and cognitive function in older adults is still controversial. A meta‐analysis was undertaken to estimate the effectiveness of intentional weight loss on cognitive function in overweight and obese adults. A structured strategy was used to search randomized and non‐randomized studies reporting the effect of intentional and significant weight loss on cognitive function in overweight and obese subjects. Information on study design, age, nutritional status, weight‐loss strategy, weight lost and cognitive testing was extracted. A random‐effect meta‐analysis was conducted to obtain summary effect estimates for memory and attention–executive domains. Twelve studies met inclusion criteria. Seven were randomized trials and the remaining five included a control group. A low‐order significant effect was found for an improvement in cognitive performance with weight loss in memory (effect size 0.13, 95% CI 0.00–0.26, P = 0.04) and attention/executive functioning (effect size 0.14, 95% CI 0.01–0.27, P < 0.001). Studies were heterogeneous in study design, sample selection, weight‐loss intervention and assessment of cognitive function. Weight loss appears to be associated with low‐order improvements in executive/attention functioning and memory in obese but not in overweight individuals.     

Effects of lifestyle interventions and long‐term weight loss on lipid outcomes – a systematic review

Weight and lipids are critical components of the metabolic syndrome, diabetes and cardiovascular disease. Past reviews considering weight loss on lipid profiles have been for ≤1 year follow‐up and/or were for very overweight, obese or morbidly obese participants. This systematic review includes lifestyle interventions for adults (18–65 years), with a mean baseline BMI < 35 kg/m², with weight and lipid differences over 2 years. Between 1990 and 2010, 14 studies were identified. Mean differences for weight and lipids were modest. However, weight loss at 2–3 years follow‐up, produced significant beneficial lipid profile changes. These were similar to previous reviews conducted on heavier target groups and/or over shorter follow‐up periods; cholesterol (1.3% decrease per kg lost) and triglycerides (1.6% fall per kg). Weight loss sustained longer than 3 years was not associated with beneficial lipid changes, suggesting that other lifestyle changes not just weight loss needs maintaining. Evidence linking lifestyle induced sustained weight loss with lipid profile changes in the long‐term for this group is limited. Probable within‐group differences (treatment vs prevention), would make further group separation prudent. Individual patient data analysis would facilitate this, uncover baseline, medication and confounding effects, and may identify successful program components enabling more effective obesity prevention and treatment strategies.     

Effectiveness of web‐based interventions in achieving weight loss and weight loss maintenance in overweight and obese adults: a systematic review with meta‐analysis

The objectives of this systematic review are to evaluate the effectiveness of web‐based interventions on weight loss and maintenance and identify which components of web‐based interventions are associated with greater weight change and low attrition rates. A literature search from 1995 to April 2008 was conducted. Studies were eligible for inclusion if: participants were aged ≥18 years with a body mass index ≥25, at least one study arm involved a web‐based intervention with the primary aim of weight loss or maintenance, and reported weight‐related outcomes. Eighteen studies met the inclusion criteria. Thirteen studies aimed to achieve weight loss, and five focused on weight maintenance. Heterogeneity was evident among the studies with seven research questions examined across interventions of varying intensity. Seven studies were assessed for effectiveness based on percentage weight change, with four studies deemed effective. Although the four meta‐analyses suggest meaningful weight change, it is not possible to determine the effectiveness of web‐based interventions in achieving weight loss or maintenance due to heterogeneity of designs and thus the small number of comparable studies. Higher usage of website features may be associated with positive weight change, but we do not know what features improve this effect or reduce attrition.     

Maintenance of weight loss after lifestyle interventions for overweight and obesity,a systematic review

Lifestyle interventions can reduce body weight, but weight regain is common and may particularly occur with higher initial weight loss. If so, one may argue whether the 10% weight loss in clinical guidelines is preferable above a lower weight loss. This systematic review explores the relation between weight loss during an intervention and weight maintenance after at least 1 year of unsupervised follow‐up. Twenty‐two interventions (during at least 1 month) in healthy overweight Caucasians were selected and the mean percentages of weight loss and maintenance were calculated in a standardized way. In addition, within four intervention groups (n > 80) maintenance was calculated stratified by initial weight loss (0–5%, 5–10%, >10%). Overall, mean percentage maintenance was 54%. Weight loss during the intervention was not significantly associated with percentage maintenance (r = ?0.26; P = 0.13). Percentage maintenance also not differed significantly between interventions with a weight loss of 5–10% vs. >10%. Consequently, net weight loss after follow‐up differed between these categories (3.7 vs. 7.0%, respectively; P < 0.01). The analyses within the four interventions confirmed these findings. In conclusion, percentage maintenance does not clearly depend on initial weight loss. From this perspective, 10% or more weight loss can indeed be encouraged and favoured above lower weight loss goals.     

Sleep duration and weight loss among overweight/obese women enrolled in a behavioral weight loss program

Objective:

The purpose of this study was to examine whether baseline sleep duration predicts weight loss outcomes in a randomized controlled trial examining a behavioral weight loss (BWL) intervention among overweight and obese (OW/OB) women with urinary incontinence; and whether participation in the BWL intervention is associated with changes in sleep duration.

Design:

Longitudinal, clinical intervention study of a 6-month BWL program.

Subjects:

Three hundred sixteen OW/OB women, with urinary incontinence (age: 30–81 years, body mass index (BMI; 25–50 kg m⁻²) enrolled from July 2004–April 2006.

Measurements:

Measured height and weight, self-report measures of demographics, sleep and physical activity.

Results:

Neither self-reported total sleep time (TST) nor time in bed (TIB) at baseline significantly predicted weight loss outcomes among OW/OB women in a BWL treatment. BWL treatment was successful regardless of how much subjects reported sleeping at baseline, with an average weight loss of 8.19 kg for OW/OB women receiving BWL treatment, versus a weight loss of 1.44 kg in the control condition. Similarly, changes in weight, BMI and incontinence episodes did not significantly predict changes in sleep duration or TIB across the treatment period.

Conclusion:

Although epidemiological and cross-sectional studies support a relationship between short sleep and increased BMI, the present study found no significant relationship between TST or TIB and weight loss for OW/OB women participating in a BWL treatment.     

Motivational interviewing to improve weight loss in overweight and/or obese patients: a systematic review and meta‐analysis of randomized controlled trials

Motivational interviewing, a directive, patient‐centred counselling approach focused on exploring and resolving ambivalence, has emerged as an effective therapeutic approach within the addictions field. However, the effectiveness of motivational interviewing in weight‐loss interventions is unclear. Electronic databases were systematically searched for randomized controlled trials evaluating behaviour change interventions using motivational interviewing in overweight or obese adults. Standardized mean difference (SMD) for change in body mass, reported as either body mass index (BMI; kg m^?2) or body weight (kg), was the primary outcome, with weighted mean difference (WMD) for change in body weight and BMI as secondary outcomes. The search strategy yielded 3540 citations and of the 101 potentially relevant studies, 12 met the inclusion criteria and 11 were included for meta‐analysis. Motivational interviewing was associated with a greater reduction in body mass compared to controls (SMD = ?0.51 [95% CI ?1.04, 0.01]). There was a significant reduction in body weight (kg) for those in the intervention group compared with those in the control group (WMD = ?1.47 kg [95% CI ?2.05, ?0.88]). For the BMI outcome, the WMD was ?0.25 kg m^?2 (95% CI ?0.50, 0.01). Motivational interviewing appears to enhance weight loss in overweight and obese patients.     

Weight‐loss interventions and gut microbiota changes in overweight and obese patients: a systematic review

Imbalances in the gut microbiota, the bacteria that inhabit the intestines, are central to the pathogenesis of obesity. This systematic review assesses the association between the gut microbiota and weight loss in overweight/obese adults and its potential manipulation as a target for treating obesity. This review identified 43 studies using the keywords ‘overweight’ or ‘obesity’ and ‘microbiota’ and related terms; among these studies, 17 used dietary interventions, 11 used bariatric surgery and 15 used microbiota manipulation. The studies differed in their methodologies as well as their intervention lengths. Restrictive diets decreased the microbiota abundance, correlated with nutrient deficiency rather than weight loss and generally reduced the butyrate producers Firmicutes, Lactobacillus sp. and Bifidobacterium sp. The impact of surgical intervention depended on the given technique and showed a similar effect on butyrate producers, in addition to increasing the presence of the Proteobacteria phylum, which is related to changes in the intestinal absorptive surface, pH and digestion time. Probiotics differed in strain and duration with diverse effects on the microbiota, and they tended to reduce body fat. Prebiotics had a bifidogenic effect and increased butyrate producers, likely due to cross‐feeding interactions, contributing to the gut barrier and improving metabolic outcomes. All of the interventions under consideration had impacts on the gut microbiota, although they did not always correlate with weight loss. These results show that restrictive diets and bariatric surgery reduce microbial abundance and promote changes in microbial composition that could have long‐term detrimental effects on the colon. In contrast, prebiotics might restore a healthy microbiome and reduce body fat.     

Effectiveness of male-only weight loss and weight loss maintenance interventions: a systematic review with meta-analysis

The objectives of this systematic review were to investigate the effectiveness of male-only weight loss and weight loss maintenance interventions and to identify intervention characteristics associated with effectiveness. In May 2011, a systematic literature search with no date restrictions was conducted across eight databases. Twenty-four articles describing 23 studies met the eligibility criteria. All studies included a weight loss intervention and four studies included an additional weight loss maintenance intervention. Study quality was mostly poor for weight loss studies (median = 3/10, range = 1-9) and weight loss maintenance studies (median = 3.5/10, range = 1-6). Twenty-three of 31 individual weight loss interventions (74%) from the eligible studies were considered effective. Meta-analysis revealed a significant difference in weight change favouring weight loss interventions over no-intervention controls at the last reported assessment (weighted mean difference -5.66 kg [-6.35, -4.97], Z = 16.04 [P < 0.00001]). Characteristics common to effectiveness were younger sample (mean age ≤ 42.8 years), increased frequency of contact (> 2.7 contacts/month), group face-to-face contact and inclusion of a prescribed energy restriction. Preliminary evidence suggests men-only weight loss programmes may effectively engage and assist men with weight loss. However, more high-quality studies are urgently needed to improve the evidence base, particularly for maintenance studies.     

Long-term weight loss effects on all cause mortality in overweight/obese populations

This systematic review assesses the long-term effectiveness of weight loss on all cause mortality in overweight/obese people. Medline, Embase and Cinahl were searched (1966-2005). Cohort studies and trials on participants with body mass index > or =25 kg m(-2), with weight change and mortality with > or =2-year follow-up, were included finally identifying 11 papers based on eight studies. There may be gender differences in the benefits for all cause mortality. The impact of weight loss in men on mortality was not clear with some studies indicating weight loss to be detrimental, while a recent cohort study showed benefits, if it were a personal decision. Other studies with no gender separation had similarly mixed results. However, one study indicated that overweight/obese women with obesity-related illness, who lost weight intentionally within 1 year, had significantly reduced mortality rates of 19-25%. In contrast, studies of overweight/obese diabetics irrespective of gender showed significant benefit of intentional weight loss on mortality in a meta-analysis, hazard ratios = 0.75 (0.67-0.83). There is some evidence that intentional weight loss has long-term benefits on all cause mortality for women and more so for diabetics. Long-term effects especially for men are not clear and need further investigation.     

A systematic review of the effectiveness of smartphone applications that encourage dietary self‐regulatory strategies for weight loss in overweight and obese adults

The aim of this paper is to systematically review the evidence to explore whether smartphone applications that use self‐regulatory strategies are beneficial for weight loss in overweight and obese adults over the age of 18 years. Sixteen electronic databases were searched for articles published up to April 2015 including MEDLINE, OVID, Ingenta, PSYCARTICLES and PSYCINFO, CINAHL, Sportdiscus, Science Direct, Web of Knowledge, Cochrane Library, JSTOR, EBSCO, Proquest, Wiley and Google Scholar. Twenty nine eligible studies were retrieved of which six studies met the inclusion criteria. Studies that recruited participants under the age of 18 years, adults with a chronic condition or did not report weight loss outcomes were excluded. Study findings were combined using a narrative synthesis. Overall, evidence suggests that smartphone applications may be a useful tool for self‐regulating diet for weight loss as participants in the smartphone application group in all studies lost at least some bodyweight. However, when compared to other self‐monitoring methods, there was no significant difference in the amount of weight lost. Findings should be interpreted with caution based on the design of the studies and the comparator groups used. Future research needs to be more methodologically rigorous and incorporate measures of whether eating habits become healthier in addition to measuring weight and BMI.     

Parent‐only vs. parent‐child (family‐focused) approaches for weight loss in obese and overweight children: a systematic review and meta‐analysis

Families are recommended as the agents of change for weight loss in overweight and obese children; family approaches are more effective than those that focus on the child alone. However, interventions that focus on parents alone have not been summarized. The objective of this review was to assess the effectiveness of interventions that compared a parent‐only (PO) condition with a parent‐child (PC) condition. Four trials using a similar between‐group background approaches to overweight and obese children's weight loss met the inclusion criteria, but only one trial reported sufficient data for meta‐analysis. Further information was obtained from authors. Meta‐analysis showed no significant difference in z‐BMI from baseline to end of treatment between the conditions (three trials) or to end of follow up (two trials). The trials were at risk of bias and no single trial was at lower risk of bias than others. There is an absence of high quality evidence regarding the effect of parent‐only interventions for weight loss in children compared to parent‐child interventions, but current evidence suggests the need for further investigation.     

Effect of chitosan on weight loss in overweight and obese individuals: a systematic review of randomized controlled trials

This article aims to determine whether chitosan, a popular, over-the-counter, weight loss supplement, is an effective treatment for overweight and obesity. It is designed as a systematic review of randomized controlled trials. The data sources include the electronic databases Medline, EMBASE, Biosis, CINAHL and Cochrane Central Register of Controlled Trials (CCTR); the specialized websites Controlled Trials, International Bibliographic Information on Dietary Supplements (IBIDS), System for Information on Grey Literature in Europe (SIGLE), Reuter's Health Service, Natural Alternatives International and Pharmanutrients; and bibliographies of relevant journal articles. Included were randomized controlled trials of chitosan with a minimum duration of 4 weeks in adults who were overweight or obese and/or had hypercholesterolaemia at baseline. Fourteen trials involving a total of 1071 participants were included in the review. Analyses involving all trials indicated that chitosan preparations result in a small but statistically significant greater reduction in body weight (weighted mean difference -1.7 kg; 95% confidence interval -2.1, -1.3 kg, P < 0.00001) compared with placebo. Analyses restricted to high-quality studies showed that reductions in weight [-0.6 (-1.2, 0.1) kg, P = 0.11] were less than in lower quality studies [-2.3 (-2.7, -1.8) kg, P < 0.00001]. Results obtained from high-quality trials indicate that the effect of chitosan on body weight is minimal and unlikely to be of clinical significance.     

A systematic review with meta‐analyses of text message‐delivered behaviour change interventions for weight loss and weight loss maintenance

Short Message Service (SMS)‐delivered behaviour change interventions are frequently used to support weight management. This systematic review examines the effectiveness of SMS‐delivered behaviour change interventions for weight management. Electronic databases were searched for randomised controlled trials (RCTs) comparing SMS‐delivered adult weight management interventions to control groups, published between 1990 and 2018. Weight change was examined using random effects meta‐analyses at intervention cessation and postintervention follow‐up. Subgroup analyses examined intervention duration, SMS frequency, theory use, SMS interactivity, and SMS tailoring. Fifteen studies met inclusion criteria (2705 participants). For weight loss interventions (n = 12, 1977 participants), the mean difference in weight change was ?2.28 kg (95% confidence interval [CI] ?3.17 to ?1.36 kg). No studies reported postintervention follow‐up. For weight loss maintenance interventions (n = 3, 728 participants), the mean difference in weight change was ?0.68 kg (95% CI, ?1.31 to ?0.05 kg), and postintervention follow‐up (n = 2, 498 participants) effects were ?0.57 kg (95% CI, ?1.67 to 0.53 kg). No subgroup differences were found. SMS‐delivered behaviour change interventions for weight loss led to significant small to moderate weight loss and weight loss maintenance compared with control groups. Evidence on long‐term effects is limited. SMS‐delivered behaviour change interventions are a potentially effective and scalable intervention option for obesity treatment.