TLDR

A new randomized controlled pilot study compared two weight loss diets in 64 men over age 55 with obesity and prediabetes. One group consumed the standard protein recommendation of 0.8 grams per kilogram of body weight per day, while the other consumed 1.4 grams per kilogram per day, with a goal of approximately 30 grams of high quality protein at four eating occasions each day. Both groups also reduced calories and exercised.

After six months, the higher protein group lost less fat free mass, improved physical performance more, and maintained a greater improvement in handgrip strength. Importantly, the higher protein intake did not worsen HbA1c, despite concerns that high protein diets could negatively affect glucose control in people with prediabetes.
The study was small and should be considered preliminary, but it reinforces an increasingly important message for older adults trying to lose weight:

The goal should not simply be to lose weight. It should be to lose fat while preserving as much muscle and physical function as possible.

Why Weight Loss Gets More Complicated as You Get Older

Losing excess body fat can provide major health benefits.

For older adults with obesity and prediabetes, weight loss can be particularly valuable because obesity is a major risk factor for progressing to type 2 diabetes.

The problem is that when you lose weight, you rarely lose only fat.

You typically lose some muscle and other fat free tissue too.

The researchers note that with conventional weight loss programs, 25 percent or more of total weight lost may come from fat free mass.

That matters at any age.

But it becomes especially important later in life.

As we age, muscle mass and strength naturally tend to decline. This age related loss of muscle is often referred to as sarcopenia, while the loss of strength is sometimes described as dynapenia.

For an older adult who already has reduced muscle reserves, losing additional lean tissue while dieting can potentially make everyday activities more difficult.

Walking.

Getting out of a chair.

Climbing stairs.

Carrying groceries.

Maintaining balance.

Remaining independent.

That means the number on the scale is only one part of a successful weight loss program.

Muscle Is Also Important for Blood Sugar Control

Muscle is not only important for strength.

It is also one of the body's major destinations for glucose.

Skeletal muscle helps remove glucose from the bloodstream in response to insulin and physical activity.

Reduced muscle mass is associated with impaired glucose uptake and greater insulin resistance, which becomes particularly relevant for someone who already has prediabetes.

This creates an interesting dilemma.

Weight loss can help reduce the risk of progressing from prediabetes to type 2 diabetes.

But losing too much muscle during that weight loss may be counterproductive for long term metabolic and physical health.

Researchers therefore wanted to know whether eating more protein could help solve part of that problem.

Why Protein Becomes More Important With Age

Protein provides amino acids your body uses to maintain and repair muscle tissue.

One amino acid in particular, leucine, plays an important signaling role in stimulating muscle protein synthesis through pathways involving mTOR.

But aging introduces another challenge known as anabolic resistance.

In simple terms, older muscle does not respond as strongly to smaller amounts of protein as younger muscle does.

That means an older adult may need a larger dose of high quality protein at a meal to produce a strong muscle building response.

The researchers note that previous work suggests approximately 30 grams of high quality protein at a meal may be useful for stimulating muscle protein synthesis in older adults.

Instead of concentrating most daily protein at dinner, spreading adequate protein throughout the day may therefore be particularly useful.

That concept became a central feature of this new study.

The Study

The researchers conducted a randomized controlled trial called VALOR UP, short for Veterans Achieving Weight Loss and Optimizing Resilience Using Protein.

The study included 64 male veterans.

Participants were:

55 years or older

Living with obesity

and

Diagnosed with prediabetes.

Their average age was approximately:

67.6 years

Average BMI was:

35.8

and average HbA1c was approximately:

6.0 percent.

Participants were randomly assigned to one of two diets for up to six months.

Group One: Standard Protein

The first group consumed approximately:

0.8 grams of protein per kilogram of body weight per day.

That corresponds to the current Recommended Dietary Allowance for protein.

Their diet provided approximately:

15 percent of calories from protein

30 percent from fat

55 percent from carbohydrates.

Group Two: Higher Protein

The higher protein group consumed:

1.4 grams of protein per kilogram of body weight per day.

Their diet provided approximately:

30 percent of calories from protein

30 percent from fat

40 percent from carbohydrates.

Participants were also instructed to consume at least 30 grams of high quality protein at each major eating occasion, using foods and supplements such as lean meats, whey protein, and high protein drinks.

Importantly, both groups were prescribed similar calorie deficits.

The researchers were not simply comparing a high calorie high protein diet with a low protein diet.

Both groups were deliberately trying to lose weight.

Everyone Exercised Too

Both groups participated in an exercise program.

Participants were prescribed:

Three 30 minute sessions of low intensity exercise per week.

One session was supervised and included activities using resistance bands along with exercises targeting:

• Strength
• Flexibility
• Balance

Participants performed two additional sessions independently.

This is important because preserving muscle during weight loss is not simply about protein.

Resistance exercise provides the stimulus telling the body that muscle tissue is still needed.

Protein provides the raw materials to help maintain and repair it.

The combination is generally more logical than relying on either strategy alone.

Both Groups Lost Weight

The weight loss program worked.

After three months, the higher protein group had lost approximately:

5.4 kilograms

or

4.7 percent of body weight.

The standard protein group lost approximately:

3.3 kilograms

or

3.1 percent of body weight.

The higher protein group therefore lost somewhat more weight early in the study.

By six months, however, the difference had essentially disappeared.

The higher protein group had lost approximately:

7.2 kilograms

while the standard protein group had lost:

7.0 kilograms.

So the biggest long term advantage was not necessarily losing more weight.

It was what happened to muscle and physical function during the weight loss.

Higher Protein Helped Preserve More Lean Mass

This is one of the most important findings.

At six months, participants eating more protein lost approximately:

0.8 kilograms of fat free mass.

The standard protein group lost approximately:

1.5 kilograms.

The researchers described this as a moderate beneficial effect favoring the higher protein diet.

That means the higher protein group still lost some lean tissue.

Protein did not completely eliminate muscle loss.

But they lost approximately 0.7 kilograms less fat free mass.

For a younger person, that difference might not seem dramatic.

For an older adult already facing age related muscle loss, preserving additional lean mass during a calorie deficit could be meaningful.

Physical Function Improved More With Higher Protein

The researchers did not only measure body composition.

They also evaluated what participants could actually do.

Their primary measure was the Short Physical Performance Battery, commonly abbreviated SPPB.

The test evaluates:

• Balance
• Walking speed
• Chair stand performance

It is commonly used to assess physical function in older adults.

At six months, the higher protein group improved their SPPB score by:

1.8 points

compared with:

1.0 point

in the standard protein group.

The difference produced a moderate effect size of:

Cohen's d = 0.68.

The researchers point out that a change of one point or more on the SPPB is considered physiologically important.

Both groups therefore improved.

But the higher protein group improved considerably more.

Why Did Both Groups Improve?

This is an important point.

The standard protein group was not doing poorly.

They were losing weight.

They were exercising.

They were participating in nutrition education.

They improved their physical performance too.

The researchers suggest the exercise program and the reduced burden of carrying excess body weight probably contributed to improved function in both groups.

Higher protein appeared to provide an additional benefit beyond those foundations.

That is very different from saying:

"Protein alone improves mobility."

The study actually supports a more complete strategy:

Calorie control plus exercise plus adequate protein.

Walking Performance Improved Faster

Researchers also measured the distance participants could walk in six minutes.

After three months, the higher protein group increased their six minute walk distance by approximately:

63 meters.

The standard protein group improved by approximately:

34 meters.

That created a moderate effect favoring the higher protein group.

By six months, the difference between groups was no longer apparent.

This suggests higher protein may have helped participants achieve some functional improvements more quickly, even though the standard protein group eventually caught up in certain measures.

The researchers themselves discuss this possibility, suggesting the higher protein strategy may accelerate some benefits of diet and exercise during weight loss.

Grip Strength Improved More Too

Handgrip strength is commonly used as a simple measure of overall muscle function in aging research.

After three months, grip strength increased by approximately:

3.7 kilograms in the higher protein group

compared with:

0.8 kilograms in the standard protein group.

The advantage persisted at six months.

Higher protein participants maintained an improvement of approximately:

3.0 kilograms

versus:

1.2 kilograms

in the standard protein group.

This is another important indication that the benefit went beyond simply changing the number on the scale.

Participants appeared to preserve and improve functional muscle capacity.

Higher Protein Also Produced More Early Fat Loss

At three months, participants in the higher protein group lost approximately:

4.7 kilograms of body fat

compared with:

2.4 kilograms

in the standard protein group.

Body fat percentage declined by:

2.4 percentage points

with higher protein

versus

1.1 percentage points

with standard protein.

Waist circumference also declined somewhat more in the higher protein group at three months.

However, these differences became much smaller by six months.

Again, the most persistent benefits at six months involved:

Physical performance

Preservation of fat free mass

and

Grip strength.

Did All That Protein Make Prediabetes Worse?

This was one of the most important questions in the study.

There has been debate over whether higher protein diets might interfere with improvements in insulin sensitivity during weight loss.

The researchers specifically wanted to ensure that increasing protein did not worsen glycemic control in participants who already had prediabetes.

The answer was reassuring.

HbA1c in the higher protein group was:

6.0 percent at baseline

5.9 percent at three months

5.9 percent at six months.

The standard protein group showed essentially the same pattern:

6.0 percent

5.9 percent

5.9 percent.

There was no meaningful difference between the groups.

So in this trial, eating 1.4 grams of protein per kilogram per day did not appear to worsen HbA1c.

But Higher Protein Did Not Cure Prediabetes Either

This needs to be stated clearly.

HbA1c did not meaningfully improve in either group.

That means the higher protein diet was not shown to reverse prediabetes.

The researchers actually expected that the weight loss and exercise might slightly improve HbA1c, but they did not observe a substantial change during the six month study.

The most reasonable conclusion is therefore:

Higher protein supported muscle and physical function without producing an obvious penalty in blood sugar control.

That is valuable.

But it is not the same as saying more protein improves glucose control.

Why 30 Grams Per Meal May Matter

One particularly interesting feature of the intervention was the emphasis on protein distribution.

The higher protein group was encouraged to consume approximately 30 grams of high quality protein at multiple eating occasions throughout the day.

This matters because older adults may not respond as strongly to small protein servings.

Imagine two people both eating 100 grams of protein per day.

Person A eats:

10 grams at breakfast

20 grams at lunch

70 grams at dinner.

Person B eats:

30 grams at breakfast

30 grams at lunch

30 grams at dinner

with additional protein from snacks.

Their total daily protein might be similar, but the second pattern provides multiple substantial protein doses capable of stimulating muscle protein synthesis throughout the day.

The present study cannot prove that protein distribution itself caused the benefits because total protein intake differed between groups too.

Still, the intervention reflects growing interest in per meal protein targets, not simply daily totals.

What Does 1.4 Grams Per Kilogram Look Like?

For a person weighing approximately:

180 pounds, or 82 kilograms

1.4 grams per kilogram would equal roughly:

115 grams of protein per day.

For a person weighing:

220 pounds, or 100 kilograms

it would equal approximately:

140 grams per day.

Those calculations illustrate the amount used in this particular study.

They should not automatically be interpreted as personalized recommendations for every older adult.

Body composition, kidney function, calorie intake, activity, health status, and individual goals all matter when determining an appropriate protein intake.

More Protein Does Not Mean Eating Only Protein

Another important detail is that the higher protein diet was still a balanced diet.

Approximately:

30 percent of calories came from protein

30 percent from fat

and

40 percent from carbohydrates.

This was not a zero carbohydrate or carnivore diet.

Participants still consumed carbohydrate while increasing protein.

The goal was simply to provide enough high quality protein to better support muscle while calories were restricted.

Weight Loss Quality Matters More Than Weight Loss Alone

This study highlights a problem with using scale weight as the only measure of success.

Imagine two people each lose 15 pounds.

Person A loses:

12 pounds of fat

and

3 pounds of lean tissue.

Person B loses:

14 pounds of fat

and

1 pound of lean tissue.

The scale says both people achieved the same thing.

Physiologically, however, the outcomes are different.

For an older adult, Person B's result may be much more desirable because maintaining muscle supports:

• Strength
• Mobility
• Independence
• Glucose disposal
• Metabolic health
• Healthy aging

That is why body composition and physical function become increasingly important when evaluating weight loss later in life.

Protein and Resistance Exercise Work Together

Another practical lesson is that protein was not used in isolation.

Every participant was exercising.

This is important because muscle is responsive to both nutrition and mechanical loading.

Resistance exercise stimulates muscle protein synthesis and provides a reason for the body to retain muscle.

Protein supplies the amino acids needed to support that remodeling.

During a calorie deficit, the combination may be particularly useful because the body is simultaneously receiving a signal to lose stored energy.

Think of resistance training as telling your body:

"We still need this muscle."

And protein helps provide the material necessary to maintain it.

Should Older Adults Trying to Lose Weight Eat More Protein?

This study suggests that some probably could benefit, particularly those at risk of losing muscle.

But we should not turn one pilot trial into a universal prescription.

The participants were a very specific population:

Men

Age 55 or older

Veterans

Living with obesity

With prediabetes

We cannot automatically assume identical results in:

• Women
• Younger adults
• People without obesity
• People with advanced diabetes
• Highly trained adults
• People with chronic kidney disease

The study itself excluded individuals with a glomerular filtration rate below 45 mL/min/1.73 m², which is important because protein recommendations may need to be individualized in people with kidney disease.

Important Limitations

The biggest limitation was the study's size.

Only 64 participants were randomized, with 32 assigned to each diet.

The researchers originally intended to enroll more people, but the COVID 19 pandemic interrupted recruitment and testing.

Because of the smaller sample, the study was not adequately powered to rely on traditional statistical significance testing for many outcomes.

Instead, the researchers emphasized effect sizes and confidence intervals.

That is why this should be considered a pilot study.

There was also meaningful attrition.

Twenty five participants in the higher protein group and 20 participants in the standard protein group completed the study, although several additional participants completed only the three month intervention because funding ended.

The intervention also combined several strategies:

• Calorie restriction
• Increased protein
• Exercise
• Nutrition education
• Behavioral support

This makes it difficult to isolate exactly how much of the improvement came from protein alone.

Finally, the study only lasted six months.

Longer trials are needed to determine whether the differences in lean mass and physical function persist over several years.

Simply Good Tip

If you are trying to lose weight after age 55, do not focus exclusively on eating less.

Think about what you are trying to keep.

A useful strategy may include:

• Regular resistance exercise
• Adequate daily protein
• Meaningful protein servings at each meal
• A moderate calorie deficit
• Slow, sustainable weight loss

In this study, the higher protein group consumed approximately 1.4 grams of protein per kilogram per day, with an emphasis on 30 gram servings of high quality protein distributed throughout the day.

That does not make 1.4 grams per kilogram the perfect target for everyone.

But it reinforces the idea that simply meeting the minimum protein recommendation may not always be optimal for preserving muscle during intentional weight loss in older adults.

The Bottom Line

Losing excess body fat can be extremely beneficial for older adults with obesity and prediabetes.

But losing muscle along with that fat is not ideal.

This new randomized pilot study suggests that increasing protein intake during weight loss may help older men preserve more fat free mass and achieve greater improvements in physical function.

Compared with participants eating 0.8 grams of protein per kilogram per day, those consuming 1.4 grams per kilogram per day:

• Preserved more fat free mass
• Improved physical performance more
• Improved grip strength more
• Lost more fat during the early phase of the intervention

At six months, the higher protein group had lost approximately 0.8 kilograms of fat free mass compared with 1.5 kilograms in the standard protein group, while their improvement in SPPB physical performance was substantially greater.

Perhaps equally important for people with prediabetes, higher protein intake did not worsen HbA1c. Both groups remained around 5.9 percent after six months.

The study is small and preliminary.

But its broader message is important:

As you get older, successful weight loss should not simply be about getting lighter.

It should be about becoming leaner while preserving the muscle, strength, and physical capacity that help keep you active and independent.

And adequate high quality protein may be one of the most important nutritional tools for helping accomplish that.

References

1. Bales CW, Miller MG, McDonald SR, Wallis JT, Yeager LA, Sloane RJ, Porter Starr KN. Influence of Protein Intake During Obesity Reduction on Physical Function and Body Habitus in Older Males With Prediabetes: A Pilot Study. Current Developments in Nutrition. 2026. doi:10.1016/j.cdnut.2026.109460.
2. The study authors cite previous research showing that weight loss in older adults can result in substantial loss of fat free mass and that adequate high quality protein and resistance exercise represent two major strategies for preserving muscle during calorie restriction.
3. The authors also cite prior research supporting the role of essential amino acids, particularly leucine, in stimulating mTOR related muscle protein synthesis and the potential importance of approximately 30 grams of protein per meal for aging muscle.

Frequently Asked Questions

How much protein did the higher protein group eat?

Participants were prescribed approximately 1.4 grams of protein per kilogram of body weight per day, compared with 0.8 grams per kilogram in the standard protein group.

How much protein did they eat at each meal?

The higher protein group was encouraged to consume approximately 30 grams or more of high quality protein at multiple eating occasions throughout the day.

Did eating more protein help preserve muscle?

Yes. At six months, the higher protein group lost approximately 0.8 kilograms of fat free mass, compared with approximately 1.5 kilograms in the standard protein group.

Did higher protein help with strength?

The higher protein group experienced greater improvements in handgrip strength. At three months, grip strength increased by approximately 3.7 kilograms compared with 0.8 kilograms in the standard protein group.

Did higher protein improve prediabetes?

Not directly. HbA1c remained essentially unchanged in both groups. The important finding was that higher protein did not appear to worsen glycemic control while helping preserve muscle and physical function.

Is 0.8 grams of protein per kilogram enough for older adults?

The study does not establish a new universal protein requirement. However, its findings suggest that consuming more than the RDA may be advantageous for some older adults during calorie restricted weight loss, particularly when muscle preservation is a priority.

Should people with kidney disease eat this much protein?

Not without individualized medical guidance. This study excluded participants with significantly impaired kidney function, so its findings should not automatically be applied to people with chronic kidney disease.