Higher Protein Diet plus Resistance Training effects on Fat Loss and Saving Muscle
The ideal diet for weight loss and overall health is not known. There is ongoing debate about what is the most beneficial balance of fats, proteins and carbohydrates. While there is significant debate about how much protein we should be eating; new dietary guidelines released in January, have increased the amount of protein they are recommending that Americans consume.
I have written 9 articles about protein for Health Matters. My intention with these 9 articles was to build a foundation of understanding of protein nutrition. I talked about just what protein is, how essential proteins are in our body, and that what we get from protein foods are the building blocks that our bodies need to make all of the proteins we must have to survive and thrive. I presented information on how different foods provide us with those building blocks. My series of articles was moving towards talking about how much protein we should be eating when I decided to pause this series of articles as it seemed likely that the recommendations would be changing.
The next few articles will discuss the new protein recommendations and if there is a good scientific basis for changing the recommendations. I am going to start out that discussion with presenting a brief summary of a study that looked at the effects of resistance training and protein intake on the preservation of muscle in people trying to lose fat.
The study “Dietary Protein and Exercise Have Additive Effects on Body Composition during Weight Loss in Adult Women” was published in The Journal of Nutrition (peer reviewed journal of the American Society of Nutrition) in 2005.
The diets in the study among the 4 groups were designed to have the same numbers of calories, same amounts of fat and same amounts of fiber. The “normal” protein diets were designed to supply the (old) Recommended Dietary Allowance of 0.8 grams protein per kilogram body weight (the amount set to prevent protein deficiency). The higher protein meals were designed to give a person 1.6 grams of protein per kilogram of body weight. Both diets included 5 servings per day of vegetables and 2–3 servings of fruits. The authors stated “The dietary differences between groups were designed to reflect a direct substitution of foods in the protein groups (meats, dairy, eggs, and nuts) for foods in the refined grain/starch groups (breads, rice, cereals, pasta, and potatoes).”
Those given the structured exercise program were told to walk for 30 minutes 5 times a week and had 2 sessions a week of resistance training on 7 weight lifting machines of at least 12 repetitions each machine. Those not given a structured exercise program were advised to get in 30 min of walking 5 times a week. Exercise diaries and accelerometers were used to document exercise.
Participants were randomized to 4 groups :
- “Normal” protein + advised to walk 30 minutes 5 times a week
- “Normal” protein + structured program including resistance training twice a week (plus walking).
- Higher protein + advised to walk 30 minutes 5 times a week
- Higher protein + structured program including resistance training twice a week (plus walking).
The study lasted 16 weeks and body composition was measured with DEXA scans. The study also looked at effects on lipids and biomarkers of obesity. See the study for details.
The first author listed on the study; Donald Layman, PhD, stated the results in an interview in this way (paraphrasing):
1) In the regular protein group who were advised to walk 30 minutes a day 5 days a week, the participants had 35% of the weight they lost be “muscle”.
2) Adding exercise to the lower protein diet reduced the muscle loss to 25% of the total weight lost.
3) Those in the higher protein diet who were advised to walk 30 minutes a day 5 days a week lost about 25% of their weight was muscle (“lean tissue”).
4) The group that was on the higher protein diet plus structured resistance exercise program had only 7% of their total weight lost be muscle (“lean tissue”).
5) Higher protein diet + resistance exercise gives you a synergistic effect. The effect of combining both interventions was (much) greater than the sum of each of the interventions added together.
6) Donald Layman stated in the interview that they did a 1 year follow up and found the benefits were maintained.
Looking at it another way: The most fat lost was in the high protein group doing structured resistance training. They lost 8.8 kilograms (19 pounds) of fat over a 16 week period. That is over a pound of fat a week, a very impressive amount of fat loss (with only 0.4 kg or 0.9 pounds loss of muscle). Those on the “normal” amount of protein without resistance training did lose 5 kg (11 pounds) of fat – but they also lost almost 6 pounds of lean tissue (presumably mostly muscle).
So the group with double the amount of protein and resistance training (just 2 sessions a week) lost 8 more pounds of fat over 16 weeks and saved 6 pounds of muscle in comparison to the lower protein group that did not do resistance training.
That is impressive! However it is important to look at the limitations of the study.
The study is limited by the sample size of only 48 subjects. This limitation is partially mitigated by the use of what is called “blocked randomization” by age and Body Mass Index.
In blocked randomization the study participants are first placed in separate groups based on a characteristic that might impact the effect on the results. They then randomize the treatments to those within each of the groups. This should minimize the likelihood that one treatment group will; by chance, have a much older group of people or those with a higher BMI.
The study was of women aged 40 to 56 (average age about 47). The results of the study should not necessarily imply that there would be a similar effect in men or for women outside of that age range.
The women in the study had a BMI ranging from 28.9 to 36.5 (greater than 25 = overweight, 30 = obesity, 40 = severe obesity). For perspective, a person who is 5 foot 6 inches weighing 200 pounds has a BMI of 32.3. The results of the study should not necessarily imply that the effects would be similar for more severely obese people.
The study was only 16 weeks. It would be more important to know the effects of these interventions over longer periods of time. However a randomized controlled prospective study for a longer period would be very costly and difficult to do.
While there are significant limitations to the study – it was very well controlled and there were significant differences in the outcomes. The outcomes are biologically plausible – it makes sense that combining resistance training with more than adequate quality protein intake would result in fat loss with less muscle loss.
The study only used 2 different amounts of protein 0.8 mg/kg and 1.6 mg/kg. This is a significant difference and does not answer the question if for example 1.2 mg/kg would give you the same results as 1.6 mg/kg. Don Layman (protein researcher and the lead author of the above study) in a review article published in 2024 said the following: “Based on the weight of available evidence, we believe that older adults benefit from daily protein intakes above the RDA ranging from 1.2 to 1.6 g/kg”. In an interview Don Layman has stated he eats about 1.5 mg of protein per kilogram of his body weight.
In future articles I will be looking at some of the other data and context of what went into the changes in protein recommendations and some of the nuances. I will also discuss some of the other aspects of the recently released recommendations.
See also my recent articles (coming soon) on the removal of the “Black Box Warning” on hormone replacement therapy and how physical activity has a tremendous impact on your health (coming soon).
Please let me know if you have any questions concerns or suggestions by emailing me at healthmattersinformation@gmail.com
Russ
Previous articles in the Protein Nutrition Series
healthmatters.fitness/uncategorized/protein/
Do higher protein diets harm our bones?
healthmatters.fitness/uncategorized/do-higher-protein-diets-harm-our-bones/
Protein, Muscle and Quality of Life
healthmatters.fitness/uncategorized/protein-muscle-and-quality-of-life/
What is the largest organ in the body?
healthmatters.fitness/uncategorized/protein-and-skin/
healthmatters.fitness/uncategorized/building-blocks-of-protein/
Amino Acids: Building Blocks of Proteins
http://healthmatters.fitness/uncategorized/amino-acids-building-blocks-of-proteins/
Essential, Nonessential and Conditionally Essential Amino Acids
What is a Limiting Amino Acid of a Food? And why is this concept important for meal planning?
How Well Each Food Supplies Us with Essential Protein Building Blocks
Statements in this article should be attributed to myself (Russ Coash, PA-C) and not to any organization I represent including my employer. I am a PA practicing in primary care, I am not an expert in weight loss , nutrition or exercise science. Please see my full list ofDisclosures, Disclaimers, Biases, and Context I created for my website/blog: healthmatters.fitness.