How Much Protein is Healthy? Unhealthy?

Per one of my previous blogs, Comparison of Food and Exercise Logging Sites, I log what I eat on Livestrong.com  A benefit of using a logging tool is seeing if I get the right amount of nutrients. Most food logging websites compare your food intake nutrient breakdown with a recommended daily intake. That can cause some concern if you find your intake is over or under the recommendations.  For example, I eat more protein than the recommended USDA guideline.   How much protein do I need?  Do I need that extra protein because of my exercise regime?  Is too much protein harmful?  Today’s blog looks into these questions.

How much protein do you need?

Recommendations on protein requirements vary widely. The USDA  food pyramid suggests that protein make up between 17% to 21% percent of total calories eaten. Twenty percent equates  to 60g of protein for a 1200 calorie diet and 100g of protein for a 2000 calorie diet.  WebMD  states an woman needs about 46 grams of protein a day (that’s about 15% for a 1200 calorie diet), adult men need about 56 grams a day¹ (that’s about 11% for a 2000 diet).  The Institute of Medicine recommends we get at least 10% and no more than 35% of calories from protein.  (see the footnotes for calculating conversions). ¹  So these three recommendations for protein range anywhere from 10% of your calories to 35% of your calories.

Does increasing protein help?

Increasing protein intake is hyped for weight loss, building muscle mass and as needed for athletic activities.  If so, how much more do you need?  Does the average person who just started an exercise program need to boost their protein intake? 

In a 2005 study, the American Journal of Clinical Nutrition found that increasing protein from 15% to 30% of total calories, and reducing fat from 35% to 20% of calories, resulted in sustained weight loss.  Thirty percent equates  to 90g of protein for a 1200 calorie diet and 150g of protein for a 2000 calorie diet. ²

Dr. Peter W. Lemon, researcher in exercise training and proper nutrition, researched protein  needs and concluded that an increase in protein intake to 1.7g per kg of body weight is beneficial for muscle growth through weight training, but only to an extent³ (see Footnotes to calculate your protein needs).  Once a certain intake level is reached, any additional protein taken in will not help build muscle mass any more.  He also notes the American diet usually contains enough protein for the average athlete. Research at Vanderbilt University said that increased protein does help for endurance athletes who train for 2-5 hours a day, because they use protein for fuel.⁴

Is too much protein harmful?

There are three reported impacts of too much protein:  overworking the kidneys,  leaching bone calcium, and gout.

Overworking the kidneys : A common misconception about excess protein in the diet is that it can cause kidney damage. Research at Vanderbilt University concluded  that no studies have found an high rate of kidney problems in strength athletes as would be expected if too much protein caused kidney damage.

Leaching bone calcium:  Another apparent misconception  is  that increased protein intake results in calcium wasting.  Studies seem to confirm that increasing protein, when exchanged calorie-for-calorie for carbohydrates, may have a favorable impact on the skeleton in healthy older men and women. 

Whether adding protein improves bones may be partly a function of how much protein the person was eating to begin with.  But in several studies comparing the bones of people eating the standard “recommended daily requirement” of protein with those eating more protein found that those who ate more protein than the standard recommendation had less bone loss.

Gout:  Increased protein consumption from red meat or seafood is associated with an increased risk of gout. But a twelve-year study at Massachusetts General Hospital showed increased consumption of high-protein, purine-rich* vegetables (e.g., asparagus, cauliflower, kidney beans, lentils, lima beans, mushrooms, navy beans) was not associated with increased risk of gout.⁵  The study  also shows that dairy products, which are also high in protein, can help reduce gout.

Conclusion

First, it’s hard to tell just how much protein is the minimum required.   Second, to a certain extent , if you want to build muscle mass through weight lifting or sustain weight loss, if you don’t eat toward the higher end of the recommended  protein range, it might help to increase protein to about 30 percent of your calories. Finally, studies show that increasing protein does no harm, as long as the protein source is not red meat.

Footnotes

*  Purine, when metabolized, turns into uric acid and excess of which causes gout

Calculating grams of protein based on percentage of daily caloric intake:  

Grams of Protein = (Desired calories * Desired protein percentage) / 4

Example: 2000 (desired calories) * .2 (20% desired protein percentage)  / 4 (grams per calorie in protein) = 100 grams protein

Calculate your protein needs for muscle building at 1.7g per kg body weight:

weight in lbs * .7711 =  grams of protein a day

References

1. Protein: Are You Getting Enough?
2.  "A high-protein diet induces sustained reductions in appetite…”, Weigle et al, American  Journal Clinical Nutrition,  2005, pages 41–8.
3. Is increased dietary protein necessary or beneficial for individuals with a physically active lifestyle?, Dr. Peter W. Lemon, Kent State,  Nutrition Reviews, 27 April 2009.
4. How Much Protein Do Athletes Need? Lee Knight Caffery, Vanderbilt University
5. Purine-Rich Foods, Dairy and Protein Intake, and the Risk of Gout in Men, Hyon K. Choi, M.D., et al, New England Journal of Medicine 2004; 350:1093-1103, March 11, 2004
6. Do low-carb diets cause bone loss?, Laura Dolson, About.com Guide, Updated June 22, 2009, About.com Health's Disease and Condition content is reviewed by our Medical Review Board