A carnivorous diet includes mostly meat, poultry and seafood. Not only would this type of diet get pretty boring, it also doesn't give you the variety in your diet recommended by the U.S. Food and Drug Administration. Without eating significant amounts of grains, fruits, vegetables and dairy, you'll be hard-pressed to get all of the different nutrients you need, and you may be at increased risk for certain health conditions.
Lacking in Certain Nutrients
Even the paleo diet and other diets recommending we eat like our ancestors recommend eating at least some foods other than meat. With a diet consisting mainly of meat, you'll have trouble getting enough carbohydrates, calcium, vitamin D, fiber, potassium and vitamin C, for example. Meat, poultry and seafood are, however, good sources of protein, iron, zinc, selenium, phosphorus and many of the B vitamins. If you followed a carnivorous diet, you'd need to take supplements to make up for some of the missing nutrients. A diet consisting mostly of meat is also likely to be high in cholesterol, fat and saturated fat, which can increase your risk for heart disease.
Increased Cancer Risk
A study published in "PLOS Medicine" in December 2007 found that people who ate the most red meat had a 20 to 60 percent increased risk for cancer compared to people who ate the least red meat. The potential increased risk for cancer from eating a meat-heavy diet may be due to the high amount of heme iron consumed, according to a meta-analysis published in "Cancer Prevention Research" in February 2011, although the mechanism for this still isn't totally clear.
Higher Risk of Heart Disease
A carnivorous diet is low in heart-healthy fiber and relatively high in saturated fat and cholesterol, factors that can contribute to heart disease risk. The strongest associations between meat and an increased risk for heart disease are for processed meats, according to a review article published in "Current Atherosclerosis Reports" in December 2012. This includes meat products such as hot dogs, ham, bacon and sausages. Avoiding or eating less of these processed meats and choosing lean cuts of meat when buying unprocessed meats can help limit your heart disease risk. Choosing fish more often can also be helpful, as seafood contains essential omega-3 fats thought to help limit heart disease risk.
Diabetes Risk Increased
The "Current Atherosclerosis Reports" review article also notes that eating higher amounts of red and processed meats may increase your risk for diabetes. Processed meats seem to cause a greater increase in your diabetes risk than unprocessed red meat, making it particularly important to eat less of these meats.