You Asked: Can You Really Eat Too Much Protein?

By , SparkPeople Blogger
For a healthy adult, eating more protein than your recommended daily range once a week or so won't have any major impact on your long-term health or weight loss (assuming you still eat approximately the same amount of calories for the day). Based on your food selections for that day, if you consume a larger-than-normal amount of protein you may notice:
  • A change in bowel habits in the next 24-48 hours (due to a lower fiber intake)
  • A sluggish or light-headed feeling (if you also ate very few carbs)
  • Some abdominal discomfort if your fat intake sky-rocketed
  • No noticeable changes at all
However, you may be wondering how a long-term high-protein diet affects your health in the long run...
Honestly, nutrition experts don’t really know for sure because the research in the area of “high protein intake” is very limited. Throughout history, there have been populations who flourished by eating a predominately high-protein (high meat) diet.  It is estimated that the Eskimo Inuit had a diet composted of approximately 45% protein with fat making up the other 55%.  During the winter season, explorers on land would survive for months on a high meat diet.  However, a high-protein diet that is extremely low in fat will result in death after several weeks.  This condition is known as “rabbit starvation” for rabbit meat is an extremely low fat meat. 
While there is currently very little research regarding disease risks associated with a high protein diet, researchers do notice a correlation between long-term high-protein intake and diseases such as osteoporosis, renal stones, kidney disease, cancer, heart disease and obesity.  In fact, a 2014 study published in Cell Metabolism reported that middle-aged adults following a high-protein diet had a 75% increase in mortality, a four-fold increase in cancer and a five-fold increase in diabetes. 

However, these associations were decreased if the protein came from plants rather than animals.  This study also looked at older adults and found the reverse.  After age 65, a moderate- to high-protein intake actually decreased cancer risk and overall mortality. Yes, the "facts" we have about protein—what is too much and for whom—can be a little confusing.

So you may be asking, “How did SparkPeople come up with its recommended protein range for me?” 

SparkPeople wants to help all adults reach optimal health and well-being for a lifetime.  We therefore use the macronutrient distribution ranges that have been established by the Food and Nutrition Board of the Institute of Medicine, The National Academies.  This board of nutrition experts obtains the published research, analyzes all the studies, and then develops nutrition guidelines for use by organizations and health care professionals.  (For the complete report, click here. The protein information can be found in chapters 10 and 11.)

As already stated earlier, there is not a great deal of research regarding an upper limit for safety regarding protein intake.  So the Food and Nutrition Board first established ranges for fat and carbohydrate (of which there is a great deal more research), based on how these nutrients impact overall health and diseases such as heart disease, cancer, diabetes, and obesity.  Then to ensure a nutritionally adequate diet, the protein range was established to balance out the fat and carbohydrate. This protein amount easily meets the amino acid needs of the body, maintains muscle mass, and promotes satiety.

The end result for the macronutrient ranges for healthy adults:
  • Carbohydrates should make up 45-65% of total calories
  • Fat should make up 20-35% of total calories
  • Protein should provide 10-35% of total calories. To determine how much you need, read this detailed article.
This distribution of calories promotes life-long, optimal health and well being for the majority of the adult population, according to the research available to date. These ranges work for both genders and various adult age groupings; fit a variety of personal food preferences, eating styles, cultural needs, and financial budgets; and work for various disease conditions and exercise routines (from the evening walker to the professional athlete or body builder). These basic guidelines help to ensure adults are meeting their needs without exposing the body to dangerous excesses in nutrients.