Choosing the right baseline weight
Percentage weight change is calculated as (usual weight − current weight) ÷ usual weight × 100. The key step is choosing the correct usual weight. The question asks about the 3-month criterion, so the baseline is the weight recorded 3 months ago, which is 52.0 kg. Her current weight is 46.5 kg. The loss is 52.0 − 46.5 = 5.5 kg, and 5.5 ÷ 52.0 × 100 = 10.6%. The denominator is always the earlier (usual) weight for the time frame being judged, never today's weight.
Interpreting the result
In nutrition assessment, a loss of more than 7.5% in 3 months is considered clinically significant, or severe, weight loss. Her 10.6% loss clearly exceeds that threshold. Together with very poor intake for the past 10 days and an acute illness, this places her in a high nutritional risk group that needs prompt nutrition support and close monitoring. The absence of edema matters too: it means her weight is not being falsely raised by retained fluid, so the measured loss reflects true tissue loss.
| Calculation | Working | Result |
|---|
| 3-month loss (correct) | (52.0 − 46.5) ÷ 52.0 × 100 | 10.6% |
| Wrong denominator | 5.5 ÷ 46.5 × 100 | 11.8% |
| 1-month loss | (48.9 − 46.5) ÷ 48.9 × 100 | 4.9% |
| 6-month loss | (53.0 − 46.5) ÷ 53.0 × 100 | 12.3% |
How the distractors are built
Each wrong option reflects a real calculation error. Dividing by the current weight gives 11.8%, which inflates the loss because the denominator is smaller. Using the weight from 1 month ago answers a different question (the 1-month loss of 4.9%), and using the weight from 6 months ago gives the 6-month loss of 12.3%. All three use real numbers from the stem, so they look plausible. Watch out! In calculation items, first match the time frame in the question to the baseline weight, then check that you divided by that baseline.
Exam takeaway
When a stem lists several weights over time, write the formula, pick the weight that matches the time frame asked, and round only at the end, as instructed. Key point! Weight loss of more than 7.5% in 3 months signals severe malnutrition risk and calls for nutrition intervention. Her height of 1.55 m could be used for body mass index, but body mass index alone would miss how quickly she is losing weight.