Weight Cycling Research Articles

Weight Cycling and Knee Joint Degeneration in Individuals with Overweight or Obesity: Four-Year Magnetic Resonance Imaging Data from the Osteoarthritis Initiative.

The aim of this study was to investigate the associations between weight cycling and knee joint degeneration in individuals with overweight or obesity with different patterns of weight change over 4years. A total of 2,271 individuals from the Osteoarthritis Initiative database were assessed (case-control study). Linear regression models using annual BMI measurements over 4years were used to classify participants as weight cyclers or noncyclers. 3-T magnetic resonance imaging was used to quantify knee cartilage transverse relaxation time (T2) and cartilage thickness annually over 4years in all subjects. Whole-Organ Magnetic Resonance Imaging Scores (WORMS) were obtained for cartilage, meniscus, and bone-marrow abnormalities in 958 subjects at baseline and at the 4-year follow-up. The longitudinal differences in cartilage T2 and thickness between weight cyclers and noncyclers were assessed using general estimating equations, whereas the differences in WORMS outcomes were compared using general linear models. No significant differences in the rate of change of cartilage thickness or T2 were found between weight cyclers and noncyclers. However, increases in maximum cartilage WORMS (P=0.0025) and bone-marrow abnormalities (P=0.04) were significantly greater in weight cyclers than in noncyclers. Although participants' intent for weight cycling in this study was unknown, weight cyclers had significantly greater increases in cartilage and bone-marrow abnormalities over 4years than noncyclers, independent of weight gain and loss.

Effect of weight cycling on progression of knee joint degenerative disease in overweight and obese individuals: 4-year mri data from the osteoarthritis initiative

Purpose: Obesity is prevalent in approximately 39.8% of US adults (data from 2015/2016), and is a risk factor for cardiovascular disease, hypertension, type 2 diabetes, and osteoarthritis (OA). Weight loss is frequently recommended for obese and overweight individuals to reduce the risk of obesity-related diseases, and has shown protective effects. However, sustained weight loss is often difficult to maintain, and an estimated 20-30% of individuals attempting weight loss experience episodic variation in body weight.

Physiology of weight regain: Lessons from the classic Minnesota Starvation Experiment on human body composition regulation

Since its publication in 1950, the Biology of Human Starvation, which describes the classic longitudinal Minnesota Experiment of semistarvation and refeeding in healthy young men, has been the undisputed source of scientific reference about the impact of long-term food deprivation on human physiology and behavior. It has been a guide in developing famine and refugee relief programs for international agencies, in exploring the effects of food deprivation on the cognitive and social functioning of those with anorexia nervosa and bulimia nervosa, and in gaining insights into metabolic adaptations that undermine obesity therapy and cachexia rehabilitation. In more recent decades, the application of a systems approach to the analysis of its data on longitudinal changes in body composition, basal metabolic rate, and food intake during the 24 weeks of semistarvation and 20 weeks of refeeding has provided rare insights into the multitude of control systems that govern the regulation of body composition during weight regain. These have underscored an internal (autoregulatory) control of lean-fat partitioning (highly sensitive to initial adiposity), which operates during weight loss and weight regain and revealed the existence of feedback loops between changes in body composition and the control of food intake and adaptive thermogenesis for the purpose of accelerating the recovery of fat mass and fat-free mass. This paper highlights the general features and design of this grueling experiment of simulated famine that has allowed the unmasking of fundamental control systems in human body composition autoregulation. The integration of its outcomes constitutes the "famine reactions" that drive the normal physiology of weight regain and obesity relapse and provides a mechanistic "autoregulation-based" explanation of how dieting and weight cycling, transition to sedentarity, or developmental programming may predispose to obesity. It also provides a system physiology framework for research toward elucidating proteinstatic and adipostatic mechanisms that control hunger-appetite and adaptive thermogenesis, with major implications for a better understanding (and management) of cachexia, obesity, and cardiometabolic diseases.

Associations Between Self-Reported Weight History and Sarcopenic Obesity in Adults with Knee Osteoarthritis.

The purpose of this study was to examine associations between self-reported weight history and sarcopenic obesity in adults with advanced knee osteoarthritis (OA). Self-reported weight history was collected from n = 151 adults (58.9% female) with knee OA and BMI ≥30 kg/m2 in a cross-sectional study. Body composition was assessed using dual-energy x-ray absorptiometry. Sarcopenic obesity was defined as appendicular skeletal muscle mass, adjusted by BMI, <0.51 kg/m2 in females and <0.79 kg/m2 in males; prevalence was 27.2%. Weight gain in the preceding year, weight gain ≥5% of body weight in the past decade, and multiple weight cycling events in life-span (loss of ≥10 lb [4.5 kg] with regain ≥3 times) were examined using logistic regression (adjusted by age, sex, and %fat mass), with the dependent variable of sarcopenic obesity presence. Weight gain in the preceding year was associated with sarcopenic obesity (odds ratio [OR]: 2.45, 95% CI: 1.02-5.87). No associations were found with weight gain in the past decade (OR: 1.04, 95% CI: 0.43-2.5) or weight cycling (OR: 0.86, 95% CI: 0.37-2.01). In adults with obesity and advanced knee OA, self-reported weight gain in the preceding year was associated with sarcopenic obesity. This patient population may benefit from recommendations that prioritize prevention of weight gain.

Body Weight Change and Cardiovascular Disease: Effect of Weight Gain, Weight Loss, and Weight Cycling

Obesity is an independent risk factor for the development and progression of cardiovascular disease (CVD). Various cardiovascular outcomes are related to the association between body weight change and CVD. Metabolically healthy obese individuals could have a better prognosis in terms of cardiovascular morbidity and mortality than metabolically unhealthy obese individuals. Smoking cessation causes significant weight gain and consequent deterioration of the metabolic profile despite not impairing the cardiovascular benefits. Intentional weight loss has a consistent cardiovascular protective effect, but unintentional weight loss due to progressive catabolism and loss of muscle mass could be associated with poor cardiovascular outcomes. Obese individuals who are successful in losing weight with subsequent regain (weight cycling) could have an unfavorable cardiometabolic profile and the risk of CVD. Further studies are needed to evaluate the impact of weight changes on CVD by identifying unknown pathophysiology and to decide appropriate management and interventions for various phenotypes of weight change.

Weight cycling practices in sport: A risk factor for later obesity?

Weight cycling, repeated cycles of weight loss and weight regain over time, is commonplace amongst many population groups. Although the effect of weight cycling on future obesity and cardiometabolic risk is still hotly debated, evidence does indicate that individuals who were normal weight prior to weight cycling are more susceptible to its adverse consequences than those who were overweight or with obesity. Athletes, and particularly those who compete in the so-called weight-sensitive sports, are prone to dieting and weight cycling practice owing to the competitive advantage to be gained from manipulating their body weight. However, in comparison with the general population, athletes tend to be leaner and weight loss phases more rapid and superimposed on a background of a high level of physical activity. In this context, it can be questioned whether weight cycling in this subpopulation will indeed increase risk for future obesity. It is perhaps surprising that despite recognition that athletes commonly partake in weight cycling during their career, studies are scarce and firm conclusions regarding the effect of this practice on future cardiometabolic risk remain to be drawn. In this review, we examine weight cycling prevalence and strategies in athletes and the current evidence relating to its short- and long-term consequences. In addition, a conceptual framework relating the dynamics of weight loss and recovery to athlete characteristics will be discussed, highlighting the need for well-controlled, prospective studies in this specific subpopulation.

Weight Cycling in Women: Adaptation or Risk?

Obesity, dieting, and weight cycling are common among reproductive-age women. Weight cycling refers to intentional weight loss followed by unintentional weight regain. Weight loss is accompanied by changes in gut peptides, adipose hormones, and energy expenditure that promote weight regain to a tightly regulated set point. While weight loss can improve body composition and surrogate markers of cardiometabolic health, it is hypothesized that the weight regain can result in an overshoot effect, resulting in excess weight gain, altered body composition, and negative effects on surrogate markers of cardiometabolic health. Numerous observational studies have examined the association of weight cycling and health outcomes. There appears to be modest association between weight cycling with type 2 diabetes mellitus and dyslipidemia in women, but no association with hypertension, cardiovascular events, and overall cancer risk. Interestingly, mild weight cycling may be associated with a decreased risk of overall and cardiovascular mortality. Little is known about the effects of weight cycling in the preconception period. Although obesity and weight gain are associated with pregnancy complications, preconception weight loss does not appear to mitigate the risk of most pregnancy complications related to obesity. Research on preconception weight cycling may provide insight into this paradox.

Changes in Cardiovascular Risk Factors Over 6 Years in Young Adults in a Randomized Trial of Weight Gain Prevention.

This study aimed to determine the impact of weight gain prevention interventions on changes in cardiovascular risk factors over 6 years. The Study of Novel Approaches to Weight Gain Prevention (SNAP) randomized 599 participants (ages 18-35; 46% with BMI 21-25; 54% with BMI 25-30) to Large Changes (produce buffer by losing 5-10 pounds initially), Small Changes (daily small changes in intake and activity) or Control and followed 355 participants with ongoing intervention and assessments through 6 years. There were no significant differences among interventions for changes in weight or cardiovascular disease (CVD) risk factors from baseline to 6 years. However, 44% of participants gained ≥5%, and only 14% lost ≥5% over 6 years. Weight changes, from baseline to year 6, were significantly associated with changes in risk factors, especially insulin and high-density lipoprotein cholesterol. Earlier weight changes (e.g., weight cycling) had no beneficial or adverse effect on changes in CVD risk factors at 6 years, independent of 6-year weight changes. Despite participation in a weight gain prevention trial, almost half of these young adults gained ≥5% or more over 6 years, with significant worsening in CVD risk factors. Greater attention to long-term weight gain prevention in young adults is needed.

The Relationship Between Pre-Pregnancy Attempts to Lose Weight and Gestational Weight Gain: An Exploratory Primary Care Prospective Cohort Study.

The primary objective of this study was to explore the association between weight cycling in the 6 months prior to pregnancy and gestational weight gain concordance with the 2009 Institute of Medicine guidelines for weight gain in pregnancy. This was a prospective cohort study. Participants were women aged 18 years or older with a singleton pregnancy who had a prenatal appointment between April 1 and August 31, 2019. Eligible women completed a questionnaire that assessed their pre-pregnancy attempts to lose weight, measured with a modified version of the Weight Cycling subscale within the Revised Restraint Scale. After delivery, participants' last recorded gestational weight before delivery, and corresponding gestational ages were obtained from prenatal records. One hundred and ninety-five pregnant women consented to participate in the study (a 95.6% response rate). Of them, 5 were excluded; therefore, 190 participants were included in the analysis. One-third of participants had attempted to lose weight in the 6 months before pregnancy. Logistic regression showed that for every one-unit increase in Weight Cycling score, the odds of excess gestational weight gain increased by a factor of 1.32. Women's pre-conceptual efforts to enter pregnancy at a lower BMI should be approached in a manner that avoids pre-pregnancy weight cycling.

Development and validation of the Multidimensional Internally Regulated Eating Scale (MIRES).

In this paper, we describe the systematic development and validation of the Multidimensional Internally Regulated Eating Scale (MIRES), a new self-report instrument that quantifies the individual-difference characteristics that together shape the inclination towards eating in response to internal bodily sensations of hunger and satiation (i.e., internally regulated eating style). MIRES is a 21-item scale consisting of seven subscales, which have high internal consistency and adequate to high two-week temporal stability. The MIRES model, as tested in community samples from the UK and US, had a very good fit to the data both at the level of individual subscales, but also as a higher-order formative model. High and significant correlations with measures of intuitive eating and eating competence lent support to the convergent validity of MIRES, while its incremental validity in relation to these measures was also upheld. MIRES as a formative construct, as well as all individual subscales, correlated negatively with eating disorder symptomatology and weight-related measures (e.g., BMI, weight cycling) and positively with adaptive behavioral and psychological outcomes (e.g., proactive coping, body appreciation, life satisfaction), supporting the criterion validity of the scale. This endeavor has resulted in a reliable and valid instrument to be used for the thorough assessment of the features that synthesize the profile of those who tend to regulate their eating internally.

Trying again (and again): Weight cycling and depressive symptoms in U.S. adults.

As the prevalence of overweight and obesity have risen over the past few decades, so have weight control attempts. Research has shown, however, that intentional weight loss results are often short-lived, with people regaining the weight over time. This can lead to weight cycling–losing and gaining weight repeatedly. Previous research, mostly done over two decades ago, concluded there was no relationship between weight cycling and psychological health. The goal of the current paper was to re-examine the relationship between weight cycling and depressive symptoms in a national sample of American adults (N = 2702; 50.7% female; mean age = 44.8 years). If, as hypothesized, there is a relationship between more frequent weight cycling and depressive symptoms, then internalized weight stigma will be examined as a potential mediator of the relationship. Results of a cross-sectional survey showed that 74.6% of adults report they have intentionally tried to lose weight. Amongst those who have tried to lose to weight, the average number of weight cycles over the lifetime was 7.82 cycles. Simultaneous regression showed that greater weight cycling was related to greater reported depressive symptoms (β = .15, p < .001), controlling for age, gender, education, income, and body mass index. Internalized weight stigma was a partial mediator of this relationship. Discussion focuses on the potential implications for weight cycling and mental health.

Attitudes and Approaches to Use of Meal Replacement Products among Healthcare Professionals in Management of Excess Weight.

Meal replacement product-based diets are an effective weight loss intervention used in the management of obesity. Historically, these diets have been underutilised by HealthCare Professionals (HCPs). An online survey of mixed methods design was distributed to HCPs to capture current perceptions and prescribing patterns of meal replacement products (MRPs) in the management of overweight and obesity. A total of 303 HCPs working in weight management across Australia began the survey and 197 (65%) completed it. While over 70% of HCPs have prescribed MRP currently or in the past, MRPs are only prescribed to a median 7% of patients seeking weight management treatment. Qualitative analysis identified potential barriers to MRP prescription, which include experience with patient non-compliance, perceived poor long-term weight loss durability and safety concerns regarding the product and its use as a total meal replacement program. Safety concerns are centred on the perceived risk of weight cycling and its potential negative psychological impact. MRP prescription is 66% more likely to occur if HCPs had formal training in the use of MRPs relative to those who did not, with a relative risk (RR) of 1.7 (95% CI 1.4, 2.0). This study highlights the potential barriers to the prescription of MRPs, which are centred around safety concerns. This also indicates that formal training may enhance the likelihood of prescribing MRPs, suggesting that once HCPs have a comprehensive understanding of the products and the evidence behind their use, their prescription is likely to be increased.

Physiological profile regulation during weight gain and loss by ovariectomized females: importance of SIRT1 and SIRT4.

Obesity in menopausal women occurs because of the systemic effects of loss of ovarian function, resulting in increased body weight and oxidative stress. Caloric restriction (CR) is essential for weight loss, since it provides benefits associated with metabolic normalization resulting from the action of sirtuins. The aim of this work was to evaluate the physiological effects of weight cycling in ovariectomized females. Females aged 2 mo (n = 8/group) were submitted to simulated surgery, ovariectomy (OVX group), and ovariectomy with weight fluctuation (WF group). In the WF group, weight cycling was performed two times, using 21 days of ad libitum commercial feed and 21 days of caloric restriction with 40% of the feed consumed by the OVX group. After 17 wk, the animals were evaluated experimentally. Weight fluctuations reduced triacylglycerol and the adipose tissue index of the WF animals, while increasing the expression of antioxidant proteins. In addition to causing fluctuations in the physiological parameters, the weight cycling led to increases of adipocyte number and serum fatty acids. These effects were reflected in increased expression of the sirtuin (SIRT) 1 and SIRT4 proteins, as well as protein complexes of the mitochondrial electron transport chain, especially in the liver and adipose tissues. The weight-cycling results suggested that mitochondrial and nuclear sirtuins were active in cellular signaling for the control of lipid metabolism, oxidative phosphorylation, and redox status. Weight cycling was able to restore the health characteristics of lean animals.

Association between weight cycling and risk of developing diabetes in adults: A systematic review and meta-analysis.

Aims/IntroductionIn this meta‐analysis, we aimed to explore the association between bodyweight cycling (weight fluctuation) and the risk of developing diabetes.Materials and MethodsWe analyzed data from eligible cohort studies that assessed the association between weight cycling in adults and the risk of developing diabetes from online databases PubMed, Cochrane Library and EMBASE databases (1966 to April 2020). We pooled data using relative risks (RRs) with a random effects model.ResultsA total of 14 studies involving 253,766 participants, including 8,904 diabetes events, were included. One study included eight independent reports, resulting in 21 reports in 14 studies. Summary analysis showed that individuals who suffered weight cycling had a higher risk of diabetes (RR 1.23. 95% confidence interval 1.07–1.41; P = 0.003). However, the association between weight cycling and the risk of developing diabetes was not observed in obese participants (body mass index ≥30 kg/m2; P = 0.08).ConclusionsThe present meta‐analysis showed that weight cycling was a strong independent predictor of new‐onset diabetes. Future studies are required to detect the causal links between weight cycling and the risk of developing diabetes.

Weight Cycling is Associated with Higher Body Mass Index and Undesirable Weight Loss Behaviors in US Army Soldiers

Weight Cycling is Associated with Higher Body Mass Index and Undesirable Weight Loss Behaviors in US Army Soldiers

Relationship between multiple weight cycles and early weight loss in patients with obesity: a longitudinal study.

To assess the relationship between multiple weight cycling (WC) and early weight loss (e-WL). Using a longitudinal prospective design conducted between May 2017 and November 2019, early weight loss was assessed at month 2 of a weight management programme in 100 adult participants with overweight or obesity, at the Outpatient Clinic of the Department of Nutrition and Dietetics at Beirut Arab University (Lebanon). Weight cycling was defined as intentional weight loss of ≥ 3kg followed by involuntary weight regain of ≥ 3kg and participants were then categorized as multiple WC if they had experienced ≥ 2 cycles. Of the 100 participants with a median age of 34.90 (22.94-50.67)years and a median BMI of 35.25 (32.75-39.48)kg/m2, 75 met the criteria for WC and displayed a lower e-WL percentage than those without WC (4.69 ± 2.78% vs. 6.58 ± 2.80%; p = 0.006). Linear regression analysis showed that e-WL was lower by ≈ 2% (β = - 1.935; 95% CL - 3.221, - 0.648; p = 0.004) in the WC group compared to the non-WC group after adjusting for age, gender and baseline BMI. In a 'real-world' clinical setting, multiple WC decreases e-WL rates. New strategies could be adopted for these patients to improve this early clinical outcome, since e-WL predicts longer-term success. III, prospective longitudinal study.

How are body mass and body attitude impacted by a behaviour change intervention in primary care? A pragmatic randomised controlled trial.

Aims:This study evaluated the effect of behaviour change interventions at Norwegian Healthy Life Centres on change in body mass index (BMI) and body attitude, and explored the predictors for change after 6 months. Methods: We randomised 118 participants to either an intervention or a control group. Eligible participants: ⩾18 years and able to take part in group-based interventions. Body attitude, weight, and height were assessed at inclusion and after 6 months. We analysed the data using simple and multiple regression. Results: Eighty-six participants completed 6-month follow-up. The study found no intervention effect on BMI or body attitude across the two groups. However, an interaction effect indicated that the leaner participants in the intervention group reduced their weight significantly (b 0.94, p < 0.001). BMI reduction was predicted by self-efficacy for physical activity and autonomous motivation for change. Weight loss was associated with impaired body attitude, body shape concern, impaired weight-related self-esteem, weight cycling, and controlled motivation for change. Improvement in body attitude was positively impacted by self-rated health, the experience of childhood respect, life satisfaction, and self-efficacy for physical activity. Impaired body attitude was predicted by body shape concern, impaired weight-related self-esteem, and controlled motivation. Conclusions: The interventions did not affect body mass on average, but promoted weight loss among the leaner participants. Because weight reduction was associated body shape concern and impaired body attitude, the study supports the claim that interventions should be weight neutral and aim to improve body image and psychological well-being rather than weight reduction.

Plasma half-life and tissue distribution of leukocyte cell-derived chemotaxin 2 in mice

Leukocyte cell-derived chemotaxin 2 (LECT2) is a hepatokine that causes skeletal muscle insulin resistance. The circulating levels of LECT2 are a possible biomarker that can predict weight cycling because they reflect liver fat and precede the onset of weight loss or gain. Herein, to clarify the dynamics of this rapid change in serum LECT2 levels, we investigated the in vivo kinetics of LECT2, including its plasma half-life and tissue distribution, by injecting 125I-labelled LECT2 into ICR mice and radioactivity tracing. The injected LECT2 was eliminated from the bloodstream within 10 min (approximate half-life, 5 min). In the kidneys, the radioactivity accumulated within 10 min after injection and declined thereafter. Conversely, the radioactivity in urine increased after 30 min of injection, indicating that LECT2 is mainly excreted by the kidneys into the urine. Finally, LECT2 accumulated in the skeletal muscle and liver until 30 min and 2 min after injection, respectively. LECT2 accumulation was not observed in the adipose tissue. These findings are in agreement with LECT2 action on the skeletal muscle. The present study indicates that LECT2 is a rapid-turnover protein, which renders the circulating level of LECT2 a useful rapid-response biomarker to predict body weight alterations.

Short-Term Sprint Interval Training Increases Maximal Oxygen Uptake Without Changing Maximal Cardiac Output

Traditional moderate intensity continuous training increases maximal oxygen uptake (VO2max). This effect is primarily attributed to an increased maximal cardiac output (Qmax), as predicted by the Fick principle. Sprint interval training (SIT) increases VO2max similar to MICT, often despite a lower training volume, but the effect on Qmax is unclear. PURPOSE: To determine the effect of 6 sessions of SIT over 2 wk on VO2max, Qmax and exercise performance in healthy, untrained adults [n=12 (9 females); 21±2 y; mean±SD]. METHODS: Training was performed on a cycle ergometer and involved a 2-min warm-up (50 W), 3 x 20-s ‘all-out’ bouts interspersed with 2-min of recovery (50 W), and a 3-min cool-down (50 W). VO2max was determined using a ramp test to exhaustion. Qmax was subsequently determined using inert gas rebreathing (Innocor) over a 2-min period of exercise performed at 90% of the peak work rate attained during the VO2max test. Pilot testing confirmed this protocol elicited VO2max over the 2-min period of Qmax measurement. The performance test was a 2 kJ/kg body weight cycling time trial. All measurements were performed twice at baseline, and reproducibility determined as a coefficient of variation (CV). The CV for VO2max, Qmax and time trial performance was 5.8, 4.7 and 4.2%, respectively. Pre- and post-training measurements were compared using a paired t-test. RESULTS: VO2max increased after SIT from 37.0±7.3 to 40.7±8.3 ml/kg/min (p<0.001), but Qmax was unchanged (17.2±3.8 vs 17.7±4.6 L/min; p>0.05). Exercise performance improved after SIT from 1040±247 to 938±238 s (p<0.001). Absolute VO2max was positively correlated with Qmax (r2 = 0.86, p < 0.001). CONCLUSION: Six sessions of SIT increased VO2max without changing Qmax in previously untrained individuals. These data support previous suggestions that the early increase in VO2max after SIT may be due mainly to peripheral responses (i.e., enhanced oxygen extraction by skeletal muscle), rather than a central change in blood oxygen delivery. Supported by NSERC

Weight change among repeat participants of an Aboriginal community-based weight loss program

BackgroundCommunity-based weight loss programs may have potential to address overweight and obesity at the population level. However, participation patterns and individual outcomes from these programs are understudied. This study examined repeat participation patterns and participant weight change between contests over seven years of an Aboriginal Australian team-based program in order to identify (1) predictors of repeat participation and (2) associations with weight change between contests.MethodsData for the 12 contests from 2012 to 2018 were merged, with probabilistic record matching. A total of 7510 enrolments were registered for the 12 contests, representing 4438 unique people. Contest lengths varied from 10 to 16 weeks in duration. Non-repeat participants were those who only competed once in the program by the end of 2018, and repeaters were those who competed in at least two contests. Associations between repeat participation and participant baseline (i.e., first participation occasion) characteristics, change in diet and physical activity and percent change in weight during the first participation occasion were examined using crossed random effects (for person and team) regression adjusted for exposure to the program. Weight percentage change between contests was calculated for consecutive participation occasions occurring at least three months apart, converted to percent change per month. Weight change was regressed on number of repeat participation occasions adjusted for age, gender, baseline weight at first participation occasion, and weight percent change in the immediately preceding contest.ResultsOne-third of the 4433 participants participated more than once, with women more likely than men to repeat. A 1% reduction in weight during a competition was associated with an increase in weight of 0.05% per month between competition end and subsequent participation. Regain was smaller the heavier participants were at their first participation.ConclusionsWhile individuals benefit from weight loss through program participation, strengthening strategies for weight loss maintenance within or following the program could improve long-term weight outcomes and reduce weight cycling.