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Boosting protein intake may be key to healthier eating, weight loss – US study

Protein is an essential component of a healthy diet, including among people on weight loss programmes. A recent study found that upping their protein intake might improve food choices and decrease the amount of sugar and refined grains consumed.

The researchers also found that among those wanting to shed kilos, increased protein intake can also reduce the loss of lean body mass.

Protein and lean body mass

Proteins are nutrients allowing the human body to function appropriately, reports Medical News Today: they help the body maintain its structure and controls functions in the body and its cells.

One challenge for people trying to lose weight is maintaining lean body mass while dumping excess fat. Lean body mass (LBM) has to do with the body’s mass that is not made up of adipose tissue or body fat. Part of this amount is made up of the muscles, or the muscle mass.

Researchers are still working to understand how protein intake affects lean muscle mass and how to best implement protein into weight-loss diets.

In this study, researchers examined how “the change in self-selected protein intake during caloric restriction (CR) alters diet quality and lean body mass (LBM).”

The study used pooled data from multiple trials and included participants who met specific eligibility criteria. Researchers evaluated 207 adults before and over six months of diets that restricted calorie intake.

All participants were either overweight or obese. All participants went through a weight loss intervention lasting six to 12 months. They all had weekly counselling sessions for the first eight weeks and follow-up visits with a registered dietitian nutritionist.

Researchers evaluated both body composition via dual-energy X-ray absorptiometry and dietary intake. They also looked at components like protein sources and diet quality. Based on the intake data, they divided participants into two groups: lower and higher protein intake.

Study author Dr Sue Shapses, a professor in the Department of Nutritional Sciences at Rutgers University-New Brunswick, told Medical News Today: “In this study design, we split the participants in half based on how much protein they consumed during the six months of weight reduction.”

Researchers found that the amount of weight loss was similar for both groups. However, among the high protein intake group, there was less loss of lean body mass.

Participants in the high protein group also made more healthy food choices, such as an increased intake of green vegetables and decreasing consumption of refined grains and added sugar.

“One surprising aspect of this study is that while all subjects were instructed to consume enough protein and a healthy diet during the weight reduction trial, it was unexpected that those who ingested less protein had fewer desirable outcomes,” said Shapses. “Those who consumed less protein also ate foods of lower quality (like more refined grains and added sugar and fewer green vegetables).”

Dr Anastasia Kalea, with the University College London Division of Medicine and who was not involved in the study, which was published in the journal Obesity, explained to Medical News Today:

“While several dietary, lifestyle, (behavioural), pharmacological or combination weight-loss interventions are promising, they often face the challenge of loss of lean body mass, which has multiple negative health implications. It affects quality of life, (and) the ability to conduct activities of daily living, has effects on neuromuscular function, emotion and psychological states, and it also affects the sustainability of weight loss because it is linked to metabolic decline.

“The holy grail of a successful weight loss intervention is to find a way to maintain LBM. Therefore, weight loss strategies that protect lean body mass are of value.”

Study limitations

This study overall indicates that increasing the protein component of diet can be beneficial for people working to lose weight. However, it has a few limitations.

For example, participants self-reported their dietary intake, so there is a possibility for errors in data collection. However, the participants received counselling about how to record food intake, and food intake data collection happened at multiple intervals, which decreased the risk for errors.

In addition, the type of protein may also impact the benefits. In this study, much of the protein participants consumed was from lean meat or plant sources. The study authors note that the study mainly included white female participants and was completed within one primary location, so the results cannot necessarily be generalised.

The methods the researchers used to measure lean body mass also didn’t differentiate between mass from organs and mass from muscles. Therefore, we cannot assume that the loss of lean body mass in the lower protein group was only from muscle loss.
Is more protein the answer?

As research moves forward in this area, more people may choose to incorporate healthy protein options into diets as they work toward reaching healthy weight levels. This concept and continued research may also help people maintain lean body mass, even as they seek to lose weight.

Shapses noted: “At any time, greater loss of LBM is not a good outcome, but it is particularly unfavourable for middle-aged and older persons who are trying to lose weight for health reasons.

“The higher protein group lost just as much fat as the lower protein group but were able to minimise the loss of LBM (suggesting an attenuated loss of muscle mass),” she said.

Kalea said that there were still knowledge gaps to cover regarding this area of research.

“We have progressed in understanding aspects of protein quality and digestibility but we need to understand better how to preserve LBM when we restrict energy for weight loss purposes; we need to understand whether a combination of different protein sources within a dietary pattern affects LBM, and how to personalise our interventions and efficiently define sufficient intake for each individual,” she said.

Study details

Higher protein intake during caloric restriction improves diet quality and attenuates loss of lean body mass

Anna R. Ogilvie, Yvette Schlussel, Deeptha Sukumar, Lingqiong Meng, Sue A. Shapses

Published in Obesity on 11 May 2022

Abstract

Objective
Higher protein intake during weight loss is associated with better health outcomes, but whether this is because of improved diet quality is not known. The purpose of this study was to examine how the change in self-selected protein intake during caloric restriction (CR) alters diet quality and lean body mass (LBM).

Methods
In this analysis of pooled data from multiple weight loss trials, 207 adults with overweight or obesity were examined before and during 6 months of CR (approximately 10 food records/person). Body composition was measured by dual-energy x-ray absorptiometry. Diet quality was assessed using the Healthy Eating Index in 2 groups: lower (LP) and higher (HP) protein intake.

Results
Participants (mean [SD], 54 [11] years; 29 [4] kg/m2) lost 5.0% (5.4%) of weight. Protein intake was 79 (9) g/d (1.0 [0.2] g/kg/d) and 58 (6) g/d (0.8 [0.1] g/kg/d) in the HP and LP groups, respectively (p < 0.05), and there was an attenuated LBM (kilograms) loss in the HP (−0.6% [1.5%]) compared with the LP (−1.2% [1.4%]) group (p < 0.01). The increased Healthy Eating Index score in the HP compared with the LP group was attributed to greater total protein and green vegetable intake and reduced refined grain and added-sugar intake (p < 0.05).

Conclusions
Increasing dietary protein during CR improves diet quality and may be another reason for reduced LBM, but it requires further study.

 

Obesity article – Higher protein intake during caloric restriction improves diet quality and attenuates loss of lean body mass (Open access)

 

Medical News Today article – Could a higher protein intake lead to healthier eating? (Open access)

 

See more from MedicalBrief archives:

 

No evidence that high-protein diet improves strength or muscle mass

 

Lower protein diet may lessen risk for cardiovascular disease

 

Low-fat vs low carb? It doesn't matter for weight loss

 

The Longevity Diet: How nutrition affects ageing and healthy lifespan – US analysis

 

 

 

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