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EMERGING SCIENCE

Emerging scienceEmerging science provides a brief summary of a selection of recently published papers or reports in the UK and elsewhere in the area of nutrition and human health

L. Wyness and A. OConnor British Nutrition Foundation, London, UK

Factors that promote or preventmaintaining weight loss

Reyes NR, Oliver TL, Klotz AA et al . (2012) Similarities and differ-ences between weight loss maintainers and regainers: a qualitativeanalysis. Journal of the Academy of Nutrition and Dietetics 112 :499505.

It is common to regain one-third to one-half of theweight lost in the rst year after losing weight (Jefferyet al . 2000; Wadden et al . 2007; Perri et al . 2008). As aresult, many individuals end up in repeated cycles of weight loss and regain. There has been considerablequantitative research on weight loss maintenance, whichsuggests that physical activity, self-monitoring of body-weight, regular weighing and continued contact with ahealth professional are associated with weight lossmaintenance. However, it remains unclear how or whyso few people are successful at weight loss maintenance.This qualitative study by Reyes et al . (2012) involvedsix focus groups to explore which factors promoted orprevented weight loss maintenance among a diverse,urban population.

The focus groups included 29 adults who had inten-tionally lost 10% of their bodyweight in the past 2years and were categorised as either regainers(n = 19) or maintainers ( n = 10) using participantsself-reported length of weight maintenance and theamount (%) regained. Regainers reported regaining 33% of their weight loss and maintainers hadregained 15%. Participants were mainly African-American (58.6%), female (65.6%) with a mean ageof 46.9 11.2 years.

Reyes et al . (2012) identied four themes thatreected similarities between regainers and maintainers,and four that reected differences between the groups.Both groups experienced lapses, used clothing t forfeedback on weight status, preferred in-personfollow-up and decreased self-monitoring of food intakeover time. When compared with regainers, maintainers

more often continued strategies used during weight loss(i.e. they weighed themselves regularly and used produc-tive problem-solving skills and positive self-talk).Regainers reported more difculty than the maintainersin independently continuing food and physical activitybehaviours during maintenance. Decreased accountabil-

ity and waning motivation were identied as barriers tomaintaining a healthy bodyweight.

Strategies to maintain bodyweight after dieting sug-gested by the authors included building social networks(e.g. internet-basedand participant-driven) that promotesupport and reinforcement over time. Given the strongempirical support for self-monitoring, applications topromote longer-term self-monitoring, such as mobilephone applications or other methods that can makeself-monitoring easier and/or more convenient, may helpwith weight maintenance. Many who lost weight,noticed weight gain based on how their clothes t ratherthan on the weighing scales. Therefore, these signals ( e.g.clothes are tighter) could be used as teachable momentsor triggers for implementing plans for reversing smallweight gains. As maintainers reported greater positiveself-talk, self-efcacy and productive problem-solvingskills, placing more emphasis on cognitive techniques forlong-term weight control may help during the weightmaintenance period.

Although this study was small and used a conveniencesampling method (which inhibits the generalisability of the ndings) and self-reported information, the ndingswere consistent with the previous work looking at suc-cessful and unsuccessful weight loss maintenance ( e.g.Byrne et al . 2003; Wing & Phelan 2005; Lindvall et al .2010). The authors suggest that weight loss mainte-nance efforts could be improved by addressing chal-lenges such as long-term self-monitoring and problem-solving skills.

Byrne S, Cooper Z & Fairburn C (2003) Weight maintenance andrelapse in obesity: a qualitative study. International Journal of Obesity and Related Metabolic Disorders 27 : 95562.

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DOI: 10.1111/j.1467-3010.2012.01985.x

2012 The Authors Journal compilation 2012 Br itish Nutrition FoundationNutrition Bulletin , 37 , 285287

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Jeffery RW, Drewnoski A, Epstein LH et al . (2000) Long-termmaintenance of weight loss: current status. Health Psychology 19:516.

Lindvall K, Larsson C, Weinehall L et al . (2010) Weight mainte-nance as a tight rope walk: a Grounded Theory study. BMCPublic Health 10 : 51. DOI: 10.1186/1471-2458-10-51.

Perri MG, Foreyt JP & Anton SD (2008) Preventing weight regainafter weight loss. In: Handbook of Obesity: Clinical Application-s,(GA Bray, C Bouchard eds), pp. 47488. Informa Healthcare:New York, NY.

Wadden TA, Butryn ML & Wilson C (2007) Lifestyle modicationfor the management of obesity. Gastroenterology 132 : 222638.

Wing RR & Phelan S (2005) Long-term weight loss maintenance.The American Journal of Clinical Nutrition 82 : 222S5S.

White rice and risk of type 2 diabetesHu EA, Pan A, Malik V et al . (2012) White rice consumption and riskof type 2 diabetes: meta-analysis and systematic review. British

Medical Journal 344 . [Epub ahead of print].Diabetes is a major public health problem globally, espe-cially in developing countries. Excess body fat is animportant determinant of type 2 diabetes and weight losscan reduce diabetes risk. Although a poor diet is knownto be a contributing factor to the diabetes epidemic, thespecic dietary strategy to prevent diabetes or delay itsonset has been debated for some time (Hu et al . 2001).Some prospective studies suggest that consumption of specic foods, such as white rice, impairs glucosemetabolism (Mohan et al . 2009; Sun et al . 2010);however, not all studies have come to the same conclu-sion (Hodge et al . 2004). Hu et al . (2012) conducted ameta-analysis on all published prospective studies evalu-ating the effect of consumption of white riceon the risk of type 2 diabetes and quantied doseresponse relations between intake of white rice and risk of type 2 diabetes.

From their literature search and study selectionprocess, the authors identied 36 potential articles forinclusion that evaluated white rice intake and incidenceof type 2 diabetes and quantied doseresponse rela-tions between intake of white rice and risk of type 2diabetes. After further examination of the full texts of these publications, four studies met the inclusion criteriaand were included in this meta-analysis. Two of thecohort studies were carried out in Asian populations(China and Japan), and the other two cohort studies inWestern populations (the USA and Australia). A total of 13 384 incident cases of type 2 diabetes occurred amongthe 352 384 participants included in the meta-analysisduring follow-up periods ranging from 4 to 22 years.Statistical analysis revealed a positive associationbetween rice intake and the risk of type 2 diabetes,comparing high and low white rice consumption levels

[pooled relative risk (RR) was 1.27; 95% condenceinterval (CI) was 1.041.54], although signicant het-erogeneity was detected (I 2 = 72.2%; Cochrane Q testP = 0.001). Rice intakes varied greatly between studies.For example, Asian populations had a higher consump-tion of white rice (34 servings/day, on average) thanWestern populations (12 servings/day, on average). Thedata were then stratied for ethnicity. Comparing thehighest with the lowest category of rice intake, Asianpopulations had a greater risk of developing type 2diabetes (pooled RR: 1.55; CI: 1.20, 2.01) than Westernpopulations (pooled RR: 1.12; CI: 0.94, 1.33). A doseresponse meta-analysis of the total population showedthat each serving per day of white rice intake was asso-ciated with an 11% increase in risk of type 2 diabetes(RR: 1.11; CI: 1.08, 1.14) ( P for linear trend < 0.001).

The authors of the study acknowledged that becauseall individual studies were observational in nature, theresults of these studies may still be subject to residualconfounding or other biases. Low socio-economic status(or indeed other factors) which is a known risk factorfor type 2 diabetes and a predictor of rice consumptionin both Asian and Western populations was notadjusted for in the statistical model. This may have ledto inaccurate results in terms of the strength of theassociation and also the direction of the effect identied.The ndings of this meta-analysis can only show asso-ciations, not cause and effect, and as type 2 diabetes isinuenced by many lifestyle factors such as obesity andinactivity, it is difcult to assess whether other factorscould have inuenced the results of this meta-analysis.In order to validate the ndings of this study, ideally, anadequately powered, randomised controlled trial inwhich white rice is modied in the intervention group isrequired. However, as this would be very difcult andtake many years to conduct, it would be more useful toinvestigate the potential mechanisms of this suggestedassociation between white rice consumption and theincreased risk of type 2 diabetes.

Hodge AM, English DR, ODea K et al . (2004) Glycaemic indexand dietary bre and the risk of type 2 diabetes. Diabetes Care

27 : 27016.Hu FB, Mason JE, Stampfer MJ et al . (2001) Diet, lifestyle, and therisk of type 2 diabetes mellitus in women. New England Journal of Medicine 345 : 7907.

Mohan V, Radhika G, Sathya RM et al . (2009) Dietary carbohy-drates, glycaemic load, food groups and newly detected type 2diabetes among urban Asian Indian population in Chennai, India(Chennai Urban Rural Epidemiological Study 59). The British Journal of Nutrition 102 : 1498506.

Sun Q, Spiegelman D, van Dam RM et al . (2010) White rice, brownrice, and risk of type 2 diabetes in US men and women. Archivesof Internal Medicine 170 : 9619.

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The satiating power of foods and drinkscontaining nutritive and non-nutritivesweetenersBellisle F, Drewnowski A, Anderson GH et al . (2012) Sweetness,satiation, and satiety. Journal of Nutrition 142 : 1149S54S. [Epub

ahead of print].

Satiation occurs during an eating episode and brings it toan end, whereas satiety starts after the end of eating andprevents further eating before the return of hunger.Enhancing satiation and satiety derived from foodstuffscan potentially affect total intake and facilitate weightcontrol. Although sweetness is a potent sensory stimulusof intake, sweet-tasting products produce satiation andsatiety as a result of their volume as well as their nutrientand energy content. There is an on-going debate as towhether energy intake from uids is as satiating as energyingested from solid foods. Bellisle et al . (2012) reviewedevidence relating to this issue andconsidered thesatiatingpower of foods and drinks containing nutritive andnon-nutritive sweeteners, as well as the brain mecha-nisms of food reward in terms of liking and wanting.

The authors concluded that uncertainty remains as towhether energy from uids is as satiating as energy fromsolids. The evidence suggests that volume can exertsatiety effects in the very short-term, whereas nutrientand energy contents play a decisive role in the longer-term. Regarding European health claims on increasedsatiety and/or reduced sense of hunger/appetite, theEuropean Food Safety Authority stated that Changes inappetite ratings after consumption of a test food

should also be observed after chronic consumption of the food ( e.g. after 1 month), and therefore tests per-formed on a single occasion would not be consideredsufcient for substantiation (EFSA Panel on DieteticProducts, Nutrition and Allergies 2011). Bellisle et al .suggested that the medium-term and longer-term effectsof a food or drink on satiation and satiety should beestablished before they are recommended in the contextof a weight control programme.

The authors reported that earlier hypotheses that low-calorie sweeteners might stimulate excessive energyintake and encourage weight gain have not been con-rmed by more recent research. Studies of free-livingusers of low-calorie sweeteners indicate that thesesweeteners can be used in the context of a healthy dietfor the purpose of limiting energy intake.

A new and interesting area of research is the investi-gation of the cerebral mechanisms underpinning foodreward. New methods of brain imaging have allowedresearchers to identify brain sites where activity corre-sponds to food liking and food wanting. Activity inthese brain sites differs according to whether the personis hungry or sated and also between overweight andnormal-weight individuals, particularly under stress.This is an interesting area for future research.

EFSA Panel on Dietetic Products, Nutrition and Allergies (2011)Draft guidance on the scientic requirements for health claimsrelated to appetite ratings, weight management, and bloodglucose concentrations released for public consultation. EFSA

Journal . Available at: http://www.efsa.europa.eu/en/consultations/ call/nda110426.pdf (accessed 28 May 2012).

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