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potential indicator for poor prognosis.

Effect of weight loss on comorbid conditions

      On the other hand, little is known about the effect of intentional weight loss driven by health carers on mortality in older adults. A randomised control trial showed no difference in mortality between those who lost a mean of 4.4 kg of body weight in comparison with the other group.²⁹

      However, mortality is only a small part of the substantial burden of disease caused by obesity‐related conditions such as hypertension, diabetes mellitus, coronary artery disease, degenerative arthritis, and cancers of the breast, uterus, and colon. Short‐term reductions in caloric intake (dieting) have favourable effects on blood pressure, cholesterol, and metabolic rate. These benefits require at least a 20% reduction in caloric intake.

      Weight loss has been shown to reduce disease‐specific risks such as hypertension and type 2 diabetes. A sample of older and overweight obese subjects from several randomized control trials (RCTs) of weight loss programs with caloric restriction and exercise or exercise alone were contacted 2.2–5.8 years after RCT termination.³⁰ Weight loss was higher in the caloric restriction group than in the exercise group and maintained in both groups in the long term. The decrease in fat mass and lean body mass was higher in the caloric‐restriction group, but in the long term, no difference in physical performance was shown between interventions.

      The Look AHEAD RCT in adults with diabetes compared intensive lifestyle intervention and diabetes care support. Weight loss, improvement in fitness, and other cardiovascular risk factors were maintained in the long term in the lifestyle intervention group.³¹ However, objective neuropathy signs were not different across the groups,³² and marginally greater cognitive decline was shown with lifestyle intervention in obese subjects during a five‐year follow‐up.³³ Despite the reduction in cardiovascular disease risk factors with intensive lifestyle intervention, no reduction in cardiovascular events was shown.³⁴

      However, it should be noted that overweight/obesity‐related comorbidities, particularly those associated with insulin resistance syndrome (e.g. hypertension, dyslipidaemia, and hyperinsulinemia) can be improved independently of weight loss.^35,36 Blood pressure can be lowered in the absence of weight loss by dietary changes.³⁷ The effect on blood pressure from non‐pharmacological interventions can be maintained for three to five years despite significant increases in body weight.³⁸ Other trials of coronary artery disease have shown prevention effects to be independent of weight loss. Finally, improvement in physical function can also be obtained without weight loss.³⁹ The data suggest that improvements in comorbid conditions can be enhanced with lifestyle changes but that the effect is independent of whether weight loss occurs.

Weight loss, a hallmark of malnutrition

Weight loss, particularly if unintentional, should be first interpreted as a sign of malnutrition. Malnutrition is a complex syndrome with different clinical presentations. After screening for malnutrition, diagnosing malnutrition according to the GLIM consensus is based on recognising etiological and phenotypic criteria (see Table 14.1).⁴⁰ Etiological factors include decreased dietary intake or assimilation, or inflammation. Phenotypic criteria are weight loss >5% within the past six months or >10% beyond six months, or low BMI. Diagnosing malnutrition based on low BMI without identifying a cause of malnutrition may overestimate the prevalence of malnutrition.

The spectrum of clinical presentations can be categorized according to the level of inflammation markers (see Table 14.1). Starvation or malnutrition due to reduced food intake or assimilation is observed with C‐reactive protein (CRP, mg L^–) <3 mg L^–1. Low‐medium intensity inflammation is described as inflammageing but was not shown to be associated with a decrease in body mass. Inflammageing can be classified as inadequate nutrition leading to increased risk for diseases associated with ageing.⁴¹ Conditions associated with medium inflammation lead to chronic malnutrition, called cachexia. Finally, high‐level inflammation associated with severe sepsis or trauma induces malnutrition with hypercatabolism (see Figure 14.1).

Starvation

      Simple starvation is caused by pure protein−energy deficiency. Starvation can be short‐term (fasting) or long‐term (chronic protein−energy undernutrition). Worldwide, starvation is most often caused by lack of food or inadequate food supply in relation to socioeconomic problems.

      Older people ingest fewer calories than younger adults. On average, people over the age of 70 consume one‐third fewer calories than younger people.⁴² About 16−18% of community‐dwelling elderly people consume fewer than 1000 kcal daily.⁴³ This reduction in intake places older adults at risk for protein−energy, vitamin, and mineral undernutrition.

In older subjects, anorexia is frequent: from 3.3% in the community to 33% in nursing homes.⁴⁴ Starvation occurring in the presence of adequate food results from the inability to swallow, a non‐functioning gastrointestinal tract, or failure of appetite (anorexia). Upper‐tract pathology, particularly due to helicobacter pilory infection, and constipation may induce anorexia. Anorexia is more frequent with depression, need for assistance with shopping or cooking, masticatory or swallowing problems, and higher CRP.⁴⁴ Anorexia may also result from changes in the physiological regulation of appetite and satiety as a physiological response to ageing.⁴⁵ The importance of understanding this relationship lies in addressing pharmacological⁴⁶ or dietary interventions⁴⁷ that may reverse this anorexia of ageing. Few diseases or conditions lead to anorexia without inflammation. Among them, having difficulty with instrumental activities of daily living due to cognitive troubles is the most prevalent. Weight loss (>5% body weight) occurs twice as frequently in older people with Alzheimer’s disease.⁴⁸ The association of basic activities of daily living dependence, oral health problems, and swallowing problems leads to a high prevalence of malnutrition.⁴⁹

Table 14.1 Malnutrition criteria according to the GLIM consensus.

      Source: Jensen et al.,⁴⁰ © 2019, John Wiley and Sons.

Table 3. Phenotypic and Etiologic Criteria for the Diagnosis of Malnutrition
Phenotypic Criteriaa	Etiologic Criteriaa
Weight Loss(%)	Low Body Mass Index (kg/m2)	Reduced Muscle Massb	Reduced Food Intake or Assimilationc,d	Inflammatione,f,g
>5% With past 6 months, or >10% beyond 6 months	<20 if <70 years, or <22 if > 70 years	Reduced by validated body composition measuring techniquesb	≤50% of ER > 1 week, or any reduced for > 2 weeks, or any chronic GI condition that adversely impacts food assimilation or absorptionc,d	Acute disease/injurye,g or chronic disease‐ relatedf,g
	Asia: <18.5 if <70 years, or <20 if >70 years

      ER, energy requirements; GI, gastrointestinal.

      ^a Requires at least 1 phenotypic criterion and 1 etiologic criterion for diagnosis of malnutrition.

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