December 2025

Long-Term Consequences of Joint Replacements

Body Mass Index (BMI) is a mathematical ratio of height to weight that healthcare professionals and researchers can readily use to categorize people’s presumed health status. While not an accurate gauge of one’s true body composition  – a ratio of muscle and fat mass relative to total body weight (with lower fat and higher muscle being indicative of a healthier risk profile) – it does serve as a quick-and-dirty way to assess one’s risks for disease.

Thus, when patients with osteoarthritis (OA) of the hip or knee are in line for replacement, after years of pain and reduced mobility, they’ve often gained more fat and lost more muscle. They also often declare that they will resume or start an exercise program once they are healed and out of pain. So a group of researchers tested the hypothesis that, after a joint replacement, patients will experience improvements in their BMI. A pool of 763 patients, 310 of the hip, 453 of the knee, from 2001-2011, was followed for 2, 5 and 10 years.

At 2 and 5 years, both groups experienced a mean rise of BMI though it was very slight: less than 1 BMI unit, though, on average, both groups were comparably considered obese. At 10 years, both groups had mean BMIs similar to when they had their replacements. However, 27% of hips and 30% of knees did reduce their BMIs.

Interestingly, 30% of hips and 32% of knees increased their BMIs. Female hip patients had increased odds of >5% increased BMI, while older knee patients had decreased odds of a 5% increase.

The authors concluded that joint replacements “should not be viewed as a gateway” to improved BMI, suggesting that a healthy lifestyle is essential at any stage.             

JBJS Nov. 2025

Protein Matters. Does When Matter, Too?

We have covered protein needs previously, here, here, here, and here, so here’s the quick synopsis: Minimal Rx – 0.8 g/kg/day; Older adults – 1.2 – 1.6 g/kg/day; Athletes – 1.5 – 2.0 g/kg/day or more, spaced out into 3-5 meals/day. But for those who work out to build muscle mass and strength, the newest ‘fad’ is about timing with current recommendations based on the idea of an “anabolic window” of 30-60 minutes after the session as optimal.

However, now some are questioning this with a variety of new protocols. One such study broke down 40 young, resistance-trained males into two groups: those who consumed the same high-protein diet with two different supplement strategies: immediately before and after the training session (Imm) and the other 3 hours before and after (3 Hrs). They all participated in the same 8 week, 3/wk full-body strength training program.

Gains in muscle mass, inverted pull-ups, and other measures of muscle strength significantly increased in both groups. Many biochemical markers of protein absorption significantly increased from pre to post in both groups.

High-protein diets enhance “muscular performance and skeletal muscle mass in resistance-trained males, irrespective of intake time”.

It appears that “total daily protein intake appears to be the primary factor in facilitating muscle growth induced by exercise.” In other words, meet the earlier Rx of 1.2 – 2.0 g/kg/day of quality proteins – animal or vegetable – in 3-5 meals/day and, whether you’re an older adult or a younger athlete, you’ll get stronger if you’ll do the muscle training.             

Frontiers in Nutr. Aug. 2025

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