Individuals with excess weight face a heightened risk of various physical and mental health conditions. Interventions targeting weight loss can improve health, with modest weight loss of five to ten percent of body weight often considered clinically meaningful for enhancing health outcomes. However, the benefits of achieving low-level weight loss ( < 5% body weight) are poorly understood. This article will systematically review relevant literature and synthesise the evidence that assessed the potential health benefits of losing less than five percent body weight.
Introduction: The Significance of Weight Loss
Compared to those with a healthy weight, individuals with excess weight are at an increased risk for many diseases and chronic health conditions, including cardiovascular diseases, type 2 diabetes, some types of cancer, anxiety, and depression. Such comorbidities can result in reduced mobility, chronic pain, and diminished quality of life. Obesity is associated with psychosocial difficulties, including lower self-esteem, heightened stress levels, eating disorders, as well as increased vulnerability to mental health disorders. People living with excess weight often face stigma and discrimination, which can result in self-stigmatisation, isolation, and self-devaluation. Obesity is also associated with substantial social and economic consequences. In the United Kingdom (UK), it is estimated that by 2050, overweight and obesity will cost the National Health Service £10 billion per year, with wider costs to society and business projected to reach £49.9 billion per year.
Why Even a Little Weight Loss Matters
Interventions targeting weight loss can improve health and prevent obesity-related co-morbidities. Weight loss among individuals with excess weight can have beneficial effects on cardiovascular disease, type 2 diabetes, sleep apnoea, chronic kidney disease, hypertension, and dyslipidaemia. Guidelines from the UK and United States of America recommend achieving modest weight loss, ranging from five to ten percent, in order to yield clinically meaningful improvements in health outcomes. As a result, weight loss of more than five percent is often cited as a key threshold for achieving clinically significant impacts and is commonly used as a target or benchmark in weight management services. While the five percent threshold provides a practical goal for weight management interventions, many participants engaging in a 12-week lifestyle intervention will not achieve this threshold. The implications of achieving a body weight reduction of less than five percent are poorly understood. Currently, interventions resulting in less than five percent weight loss are often deemed ineffective; however, they may still offer benefits in improving health outcomes, particularly for individuals living with obesity. Exploring the potential health impacts of less than five percent weight loss could be useful in informing policy and practice.
The Study: Health Benefits of Losing Less Than 5% Body Weight
The primary aim was to systematically review and synthesise evidence that assessed the health benefits of losing less than five percent body weight on health outcomes or indicators such as, cardio-metabolic markers, wider physical markers, and psychosocial markers from controlled trials. This study further aimed to describe findings by intervention type and to stratify results by baseline BMI and level of weight loss where data allowed.
Methodology
This systematic review was registered with PROSPERO (CRD42023406342) conducted and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist [36]. To be eligible for inclusion, studies needed to be randomised or quasi-randomised controlled trials (RCTs) or intervention studies with pre-post measures. The included exposures were weight loss interventions with lifestyle (physical activity/diet) or pharmacological components. The participant criteria were adults (18 years or older) who lost less than five percent of their body weight following an intervention. Included outcomes were any type of health measures, including physical, mental, or behavioural. The health measures of interest were broad, and searches were structured without outcome terms to ensure all relevant outcomes were captured. Findings were required to be stratified by percentage weight loss. Studies from any country, language or published at any time were included. Studies were excluded if they were non-peer reviewed articles (dissertations, conference abstracts, grey literature), if they did not include any relevant health measures, if they only presented outcomes by overall weight change (without any stratification by percentage weight loss), or if the weight loss intervention was surgical. Surgical interventions, including bariatric surgery, were excluded due to the difference in intervention intensity and the percent weight loss typically observed (typically 20 to 30% weight loss) [37,38,39].
Read also: Weight Loss Guide Andalusia, AL
Searches of the following electronic databases were conducted in March 2023: Medline (Ovid), Embase (Ovid), PsycINFO (Ovid), CINAHL (Ebsco), Cochrane Library CENTRAL, Applied Social Sciences Index and Abstracts (ProQuest), and Web of Science-Social Science Citation Index and Emerging Sources Citation Index (see Tables S1 in supplementary file for the full search strategies). The search strategy was developed by JP with oversight and input from CS (information specialist). The searches were conducted by JP and the results were firstly imported into EndNote version 20 [40] to remove duplicates, before importing into EPPI-Reviewer Version 6 software [41] to again remove duplicates and for screening and review management. Articles were double screened on title and abstract and full text by a team of reviewers (JP, SM, JC) and discrepancies were jointly reconciled.
The Critical Appraisal Skills Programme (CASP) checklist [42] was used to assess the bias in the included studies. Bias assessment for each article was conducted independently in duplicate by a team of reviewers (JP, SM, DD) with discrepancies jointly reconciled. Studies were categorised as having a high, moderate or low risk of bias (see Table S2 in supplementary file for further details).
Data was extracted for participants achieving less than five percent weight loss, which may have been the whole study population or, more often, a subset of the original study population. Reported sample sizes reflect the groups relevant to our research question, often subgroups of whole study cohorts. Data extracted included study characteristics (primary author, country, year of publication), participant characteristics where possible (sample size, stratified sample size, age, baseline BMI, comorbidities), intervention characteristics (intervention type, duration, follow up), outcome details (category, measure, key finding). Corresponding authors were contacted to request additional data, where required, for the meta-analysis. Eight studies’ corresponding authors were contacted, of whom two responded with the required data. We specifically asked for mean score change, effect size measurements (e.g., standard deviation), and stratified sample sizes.
Findings across included studies were synthesised narratively. Due to the heterogeneity and constraints on the available data, meta-analysis was not possible. The data presented several constraints, such as outcomes being stratified by different weight-loss groups and values being inconsistently reported. Few studies reported the overall baseline values, while other studies reported the values by intervention group. Follow-up outcomes were also often reported only by weight-loss groups. Additionally, there were missing sample sizes and precision estimates, which further complicated the analysis.
Study characteristics were tabulated and health markers and indices, identified across the included studies, were classified into broader health categorises. The health markers and indices were categorised as metabolic markers, cardiovascular markers, anthropometric markers, quality of life indices, inflammatory biomarkers, renal and hepatic markers, psychosocial and behavioural measures, pulmonary function, total mortality, ovulatory function, and muscle strength.
Read also: Beef jerky: A high-protein option for shedding pounds?
Additionally, the findings for each study were classified into: ‘improvements’ where all studied health measures showed improvements either statistically significant or not, ‘mixed results’ where the studied health measures either showed no significant change or a mixture of improvements and declines; and ‘worsening’ where all the studied health measures that showed either statistically significant or non-significant deterioration. The overall impact of weight loss interventions on health measures of participants that loss less than five percent body weight in each study included. Findings were considered by follow-up duration to assess impacts on health measures, over time. Studies with less than 6 months follow up were compared to those with 6 months or greater, and then studies with less than 12 months follow up to those with 12 months or greater.
Study Selection
The searches resulted in 13,905 articles, of which 5778 were duplicates, leaving 8127 original articles to screen on title and abstract. After screening on title and abstract, 7158 were excluded (3943 manually and 3215 excluded by the machine learning predictive algorithm) and 969 articles were included for full-text screening, of which 11 reports were not retrieved in full-text. Application of the classifier provided articles with scores ranging from 6 to 92 which were sorted in descending order and articles with a score of 70+ were double screened; no articles were included through this process. Studies with a score between 60-69 were screened on title and abstract by one reviewer and no relevant papers were found. We excluded 891 articles that did not meet the inclusion criteria for publication type, study design, age of participants, exposure, outcome measure and stratification of results. This led to the final inclusion of 70 studies from 68 articles.
Quality of Studies
Overall, the studies were predominantly assessed as having a moderate risk of bias (n = 36; 53%), followed by high (n = 18; 26%) and low (n = 14; 21%). The typical issues were around randomisation methodology.
Study Description
Of the 70 included studies, the majority were randomised controlled trials (n = 47); the remaining study designs (n = 23) included before-after non-randomised intervention studies, clinical trials, cohort studies, prospective studies, and secondary analyses of trials/interventions. Most studies (n = 63) were conducted in high-income countries, including the USA (n = 34), UK (n = 3), Canada (n = 3), Japan (n = 3), and Australia (n = 2). Total study participants in the included studies ranged from 14 to 10,742. Follow-up periods ranged from six weeks to 7.4 years, with the majority of the studies (n = 54) having follow-up periods of 12 months or less.
Various intervention types were assessed but were predominantly lifestyle interventions (n = 47), with fewer studies assessing pharmacological only interventions (n = 2) or a combination of lifestyle and pharmacological (n = 21). Lifestyle interventions typically included components focussed on calorie restriction, physical activity promotion programmes, behavioural modifications, or lifestyle counselling. The most common drug utilised for pharmacological interventions were Orlistat (n = 6), Sibutramine (n = 4) and Metformin (n = 2).
Read also: Inspiring Health Transformation
The weight loss stratifications in included studies were most commonly less than five percent (n = 44), less than three percent (n = 7), or greater than two percent to less than five percent (n = 7). Studies were described based on their average baseline BMI into categories including overweight and higher (n = 42), obesity class-1 and higher (n = 9), and obesity class-2 and higher (n = 1), with 18 studies not reporting baseline BMI values. Study cohorts were also described based on inclusion criteria for co-morbidities, with the majority not including co-morbidities (n = 39), followed by metabolic syndrome (n = 18), diabetes (n = 8), and hepatic disorders (n = 6).
While statistically significant improvements were highlighted (Table 2), non-significant improvements were classified as improvements. Low levels of weight loss, such as a 0-2% reduction in body weight, can lead to small improvements in health outcomes that may not reach statistical significance, particularly in small studies.
A total of 201 unique health markers and indices were reported across the 70 included studies (refer to Table S3 in the supplementary file for a detailed list). A total of 11 health categories classified health measures, including health markers and indices. These categories were reported a total of 137 times across the 70 studies: metabolic markers (n = 42), cardiovascular markers (n = 32), anthropometric measures (n = 19), quality of life indices (n = 10), inflammatory biomarkers (n = 10), renal and hepatic markers (n = 9), psychosocial and behavioural measures (n = 8), pulmonary function (n = 3), total mortality (n = 2), ovulatory function (n = 1), and muscle strength (n = 1).
Key Findings: The Positive Impact of Even Small Weight Loss
The findings of the review indicated that even a weight loss of less than 5% could yield positive health outcomes. Overall, 60% of studies reported improvements, 37% found no change or mixed results, and 3% observed a worsening of health markers or indices. Based on the available data, 87% of participants (n = 15,839) in the studies reported improvements in health markers or indices as a result of low-level weight loss.
Improvements in Health Markers
The review categorised health markers into 11 categories, with the most common being metabolic markers (n = 42) and cardiovascular markers (n = 32). This suggests that even small amounts of weight loss can have a positive impact on these critical areas.
- Metabolic Markers: These include measures like blood sugar levels, insulin sensitivity, and cholesterol levels. Improvements in these markers can reduce the risk of developing type 2 diabetes and metabolic syndrome.
- Cardiovascular Markers: These include blood pressure, heart rate, and measures of blood vessel function. Improvements in these markers can reduce the risk of heart disease and stroke.
- Anthropometric Measures: These include body weight, BMI, waist circumference, and body fat percentage. Even small reductions in these measures can have a positive impact on overall health.
- Quality of Life Indices: These include measures of physical function, emotional well-being, and social interaction. Improvements in these indices can enhance overall quality of life.
- Inflammatory Biomarkers: These include measures of inflammation in the body. Reductions in these markers can reduce the risk of chronic diseases like heart disease and cancer.
- Renal and Hepatic Markers: These include measures of kidney and liver function. Improvements in these markers can reduce the risk of kidney and liver disease.
- Psychosocial and Behavioural Measures: These include measures of mood, self-esteem, and eating behaviours. Improvements in these measures can enhance mental health and well-being.
- Pulmonary Function: These include measures of lung function. Improvements in these measures can improve breathing and reduce the risk of respiratory problems.
- Total Mortality: This is a measure of the number of deaths in a population. Weight loss can reduce the risk of death from all causes.
- Ovulatory Function: This is a measure of the ability to ovulate. Weight loss can improve ovulatory function in women with polycystic ovary syndrome (PCOS).
- Muscle Strength: This is a measure of muscle strength. Weight loss can improve muscle strength.
The Impact of Different Intervention Types
The majority of the included studies used lifestyle interventions (n = 47), with fewer studies assessing pharmacological only interventions (n = 2) or a combination of lifestyle and pharmacological (n = 21). Lifestyle interventions typically included components focused on calorie restriction, physical activity promotion programmes, behavioural modifications, or lifestyle counselling. This suggests that lifestyle changes are an effective way to achieve even small amounts of weight loss and improve health outcomes.
The most common drugs utilized for pharmacological interventions were Orlistat, Sibutramine, and Metformin. These drugs work through different mechanisms to promote weight loss, but they all have the potential to improve health outcomes.
Stratification by Baseline BMI and Level of Weight Loss
The weight loss stratifications in included studies were most commonly less than five percent (n = 44), less than three percent (n = 7), or greater than two percent to less than five percent (n = 7). Studies were described based on their average baseline BMI into categories including overweight and higher (n = 42), obesity class-1 and higher (n = 9), and obesity class-2 and higher (n = 1), with 18 studies not reporting baseline BMI values. This suggests that even people who are already overweight or obese can benefit from losing a small amount of weight.
Study cohorts were also described based on inclusion criteria for co-morbidities, with the majority not including co-morbidities (n = 39), followed by metabolic syndrome (n = 18), diabetes (n = 8), and hepatic disorders (n = 6). This suggests that people with co-morbidities can also benefit from losing a small amount of weight.
Real-World Strategies for Achieving Modest Weight Loss
Given the evidence that even small amounts of weight loss can be beneficial, what are some practical strategies for achieving this? Here are some evidence-based approaches:
Dietary Changes
- Focus on Whole Foods: Prioritize fruits, vegetables, whole grains, and lean protein sources. These foods are nutrient-dense and lower in calories than processed foods.
- Reduce Processed Foods and Added Sugars: Limit your intake of processed foods, sugary drinks, and desserts. These foods are often high in calories and low in nutrients.
- Mindful Eating: Pay attention to your hunger and fullness cues. Eat slowly and savor your food. Avoid distractions while eating, such as watching TV or using your phone.
- Portion Control: Be mindful of portion sizes. Use smaller plates and bowls to help control your intake.
- Soluble Fiber: Eating soluble fiber may help promote weight loss and have other health benefits. But fiber from whole plant foods is better for weight loss than fiber supplements. Viscous soluble fibers such as pectins, beta-glucans, psyllium, glucomannan, and guar gum all thicken in water, forming a gel-like substance that sits in your gut. This gel slows the emptying of your stomach, increasing digestion and absorption times. The end result is a prolonged feeling of fullness and reduced appetite. Rich sources include: beans and legumes, flaxseeds, asparagus, Brussels sprouts, and oats.
Increased Physical Activity
- Aim for 30 Minutes of Moderate-Intensity Exercise Most Days of the Week: This could include brisk walking, jogging, swimming, or cycling.
- Incorporate Strength Training Exercises at Least Twice a Week: Strength training can help build muscle, which can boost your metabolism and help you burn more calories.
- Find Ways to Move More Throughout the Day: Take the stairs instead of the elevator, walk during your lunch break, or do some light stretching while watching TV.
Behavioural and Lifestyle Modifications
- Self-Monitoring: Keep a food diary and track your physical activity. This can help you identify patterns and make adjustments to your behaviour.
- Set Realistic Goals: Set small, achievable goals. This will help you stay motivated and avoid feeling overwhelmed.
- Seek Support: Enlist the help of friends, family, or a healthcare professional. Having a support system can make it easier to stick to your weight loss plan.
- Environmental Management: A significant part of weight loss and management may involve restructuring the environment that promotes overeating and underactivity. The environment includes the home, the workplace, and the community (e.g., places of worship, eating places, stores, movie theaters). Environmental factors include the availability of foods such as fruits, vegetables, nonfat dairy products, and other foods of low energy density and high nutritional value. Environmental restructuring emphasizes frequenting dining facilities that produce appealing foods of lower energy density and providing ample time for eating a wholesome meal rather than grabbing a candy bar or bag of chips and a soda from a vending machine. Busy lifestyles and hectic work schedules create eating habits that may contribute to a less than desirable eating environment, but simple changes can help.
- Eating Environments: A significant part of weight loss and management may involve restructuring the environment that promotes overeating and underactivity. The environment includes the home, the workplace, and the community (e.g., places of worship, eating places, stores, movie theaters). Environmental factors include the availability of foods such as fruits, vegetables, nonfat dairy products, and other foods of low energy density and high nutritional value. Environmental restructuring emphasizes frequenting dining facilities that produce appealing foods of lower energy density and providing ample time for eating a wholesome meal rather than grabbing a candy bar or bag of chips and a soda from a vending machine. Busy lifestyles and hectic work schedules create eating habits that may contribute to a less than desirable eating environment, but simple changes can help.
The Importance of Maintenance
It's not enough to eat healthy foods and exercise for just a few weeks or months. To keep off extra weight, you should make these healthy changes a way of life. Think about negative habits or other challenges that have kept you from losing weight in the past. You'll likely have some setbacks on your weight-loss journey. But don't give up after a setback. Simply start fresh the next day. Remember that you're planning to change your life. It won't happen all at once. Stick to your healthy lifestyle.
Conclusion: Precious Weight Loss Benefits
The evidence suggests that even a small amount of weight loss, less than 5% of body weight, can have a significant positive impact on health. This includes improvements in metabolic markers, cardiovascular markers, and overall quality of life. By making small, sustainable changes to your diet and lifestyle, you can achieve these benefits and improve your overall health and well-being. Remember, the journey of a thousand miles begins with a single step. Start small, be consistent, and celebrate your progress along the way.
#