12 studies were evaluated regarding the association between underweight or weight loss and depression in adults over age 65. Four studies report an association between weight loss or poor nutritional status and depression, while two studies report no association between low BMI and depression. Additional studies report that weight loss may be common in depressed individuals with Alzheimer's disease, individuals who are recently widowed, demented individuals and individuals on antidepressant therapies. Further research is needed in this area.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.

All seven studies that were evaluated report an association between underweight, weight loss and poor nutrition status and prevalence of infection in adults over age 65.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.

Eight studies were evaluated regarding the association between underweight or weight loss and decreased appetite in adults over age 65. Studies report an association between reduced appetite and poor protein and energy intake, resulting in weight loss and poor nutritional status.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.

15 studies were evaluated regarding the association between underweight or weight loss and a decrease in the activities of daily living in adults over age 65. All studies report an association between poor nutritional status, frailty, underweight or weight loss with a decrease in the activities of daily living.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.

Twenty-six studies were evaluated regarding the association between underweight and weight loss and neurological disease in adults over age 65. All studies report an association between underweight and weight loss in patients who have cognitive impairment, including Alzheimer's disease and other dementia disorders, Parkinson's disease and stroke. 

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.

Five studies support an association between underweight or unintended weight loss and increased mortality, but the definition is inconsistent. One study reported that mortality was 50% for subjects with a BMI under 20kg/m², but additional research suggests that the current BMI thresholds may not apply to the elderly. Two studies report that weight loss was associated with a two- to 10-fold increased risk for death and one study reported that those who were severely underweight were four times more likely to have unintentional weight loss of 10 lbs in six months. Further research is needed in these areas.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.