Balance of muscle and fat cells representing healthy weight loss.

Losing Weight and Keeping It Off: The Unexpected Key to Longevity

Kai Mendoza in Health & Wellness November 2025 • 4 min read.

"New research reveals that weight loss isn't just about the numbers on the scale; it's about maintaining lean muscle mass for a longer, healthier life."

For years, we've been told that losing weight is a key to a longer, healthier life. Countless diets and fitness plans promise quick results and a slimmer physique. But what if the secret to longevity isn't just about shedding pounds, but about how you lose them?

A groundbreaking study published in Clinical Nutrition sheds light on this very question. Researchers investigated the impact of weight loss on one-year mortality rates in hospital patients, taking into account not just Body Mass Index (BMI), but also Fat-Free Mass Index (FFMI) – a measure of lean muscle mass. The findings challenge conventional wisdom and offer a more nuanced understanding of the relationship between weight loss and overall health.

The study highlights the importance of preserving muscle mass during weight loss, suggesting that it's not just about the number on the scale, but the composition of your body that truly matters. This has profound implications for how we approach weight management, especially for those at risk of malnutrition or chronic disease.

Why Muscle Matters: Unpacking the Study's Key Findings

Balance of muscle and fat cells representing healthy weight loss.

The study, conducted at the VU University Medical Center in Amsterdam, followed 769 patients. Researchers tracked their weight loss, BMI, FFMI, and one-year mortality rates. Critical weight loss (CWL) was defined as more than 5% weight loss in the previous month or more than 10% in the previous six months.

Here's where it gets interesting: researchers discovered that weight loss alone didn't always translate to a higher mortality risk. The key differentiator was FFMI. Patients who experienced critical weight loss and had low FFMI were at significantly higher risk of death than those who maintained their muscle mass.

Critical Weight Loss (CWL): Defined as >5% loss in the previous month or >10% in the last six months.
Fat-Free Mass Index (FFMI): Measures lean muscle mass relative to height.
BMI Cut-offs: Used to classify patients as underweight, normal weight, or overweight.
Key Finding: CWL + low FFMI = Higher mortality risk. CWL + normal FFMI = Not significantly higher mortality risk.

These results align with the guidelines that the European Society for Clinical Nutrition and Metabolism (ESPEN) consensus suggests that a patient is only considered to be malnourished if the weight loss had led to a considerable depletion of energy or protein reserves, represented by BMI or FFMI below the suggested cut-off points.

The Takeaway: Focus on Fitness, Not Just the Scale

This study offers a powerful message: when it comes to weight loss, focus on preserving and building muscle mass. Incorporate strength training into your fitness routine, prioritize protein in your diet, and work with healthcare professionals to ensure you're losing weight in a healthy and sustainable way. Because at the end, its not about the weight in scale but lean muscle for extended and happier life.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.clnu.2017.08.024, Alternate LINK

Title: The Association Of Weight Loss With One-Year Mortality In Hospital Patients, Stratified By Bmi And Ffmi Subgroups

Subject: Critical Care and Intensive Care Medicine

Journal: Clinical Nutrition

Publisher: Elsevier BV

Authors: Marian A.E. De Van Der Schueren, Malon De Smoker, E. Leistra, H.M. Kruizenga

Published: 2018-10-01

Everything You Need To Know

What were the main findings regarding weight loss and mortality rates in the Clinical Nutrition study?

The study published in *Clinical Nutrition* revealed that the impact of weight loss on one-year mortality rates in hospital patients depends on both Body Mass Index (BMI) and Fat-Free Mass Index (FFMI). The key finding was that Critical Weight Loss (CWL) combined with low FFMI significantly increases mortality risk, while CWL with normal FFMI does not show a significantly higher risk. This suggests that preserving muscle mass is crucial during weight loss to ensure better health outcomes.

What is Critical Weight Loss (CWL) and why is it a significant factor in the context of this research?

Critical Weight Loss (CWL) is defined as losing more than 5% of body weight in the previous month or more than 10% in the previous six months. It's an important marker because it indicates a significant and rapid decline in body mass, which can have serious health implications, especially when coupled with a loss of lean muscle mass as measured by Fat-Free Mass Index (FFMI).

What is Fat-Free Mass Index (FFMI), and why is it considered a crucial indicator in assessing the health impact of weight loss?

Fat-Free Mass Index (FFMI) is a measure of lean muscle mass relative to height. It's crucial because it helps assess the quality of weight loss. Maintaining a healthy FFMI during weight loss is essential for overall health and longevity, as demonstrated by the study showing that individuals with adequate FFMI levels did not experience increased mortality risk, even with Critical Weight Loss (CWL).

What are the broader implications of the study's findings for weight management strategies and future research?

The study's findings imply that traditional weight loss approaches focused solely on reducing the number on the scale may be inadequate or even harmful. It suggests a shift towards strategies that prioritize preserving and building lean muscle mass, such as incorporating strength training and ensuring adequate protein intake. Future research should explore targeted interventions for different populations to optimize body composition during weight management.

What practical steps can individuals take to ensure they are losing weight in a healthy way that preserves lean muscle mass and supports overall health?

To promote healthy weight loss and maintain lean muscle mass, it's important to incorporate strength training exercises into your fitness routine, prioritize protein-rich foods in your diet, and consult with healthcare professionals or registered dietitians for personalized guidance. Monitoring both Body Mass Index (BMI) and Fat-Free Mass Index (FFMI) can provide a more comprehensive understanding of your body composition and help you tailor your approach to weight management.