In every argument about the macro-nutrients, everyone is talking about the amounts of carbohydrates and fats one needs, about "good" and "bad" carbohydrates and "good" or "bad" fats. However, when it comes to protein, the discussion is over and everyone agrees, the more protein the better. But what are the side effects of protein?
Surely a diet rich in protein will help you lose pounds and is a diet that is being recommended by many health gurus. And because carbohydrates are accused of being responsible for diabetes, you can think that a diet with few carbohydrates and a lot of animal protein is the best option for diabetics.
However, studies shows that if you suffer from insulin resistance or you are diabetic, taking large amounts of protein (such as Whey, which gives you a good amount of protein per shake) may potentially aggravate your problem.
As high amount of protein is considered a quantity that is more than 35% of your total calories. For example, if you consume 2000 calories, 35% is 175g of protein per day  and if you drink 2-3 shakes per day, along with the protein you get from the rest of your diet, then 175g is a number that can be easily reached.
Consuming large quantities of protein can increase plasma glucose and insulin levels, reduce cells' sensitivity to insulin and cause diabetes [2, 3, 4, 5, 6], especially when talking about low carbohydrate and high animal protein diet [7, 8].
Also, consumption of large amounts of animal protein increases microalbuminuria , which is considered to be evidence of onset of diabetic nephropathy , but can also suppress your liver (since is the liver that process the protein), leading to an increase in the concentration of amino acids in the blood, also cause nausea or diarrhea and in excessive amounts, cancer and even death, according to an article published in International Journal of Sport Nutrition and Exercise Metabolism [11, 12].
In fact, researchers have been examining the effects of the protein on gluconeogenesis, glucose synthesis from non-carbohydrate sources, like in one study where examined the glucagon and insulin levels after consumption of various protein sources .
Their results showed that even in healthy people, 25g of glucose with 30g of protein (Whey-WPH, Pea-PPH) cause too much increase in plasma glucose and glucagon (and therefore gluconeogenesis) in 20' after its consumption.
This is important for people with type 2 diabetes (or insulin resistance), where their body is insulin resistant and can not stop gluconeogenesis, resulting in high blood sugar. Under normal circumstances and when cell are sensitive to insulin, insulin stops the action of glucagon and thus prevents the release of more sugar in the blood .
Certainly there are and different opinions. For example, in one study, 50g of protein did not triggered a high blood glucose concentration . However, in this study they used beef, a slow-absorbing protein rather than a fast protein, like Whey, which they used in the previous study.
Of course I am not saying to avoid consuming any protein or that it's not necessary to use shakes after a workout. However, if you suffer from diabetes or insulin resistance (and certainly many who do not exercise for a while or do not care about their diet, have a form of insulin resistance), you should be careful with the amounts of protein you getting, because as you will see, large amounts of protein does not necessarily make good, and animal protein in general has also been linked to cancer. Even after intense weight training, the amount of protein needed for muscle protein synthesis and repair is only 20 grams .
It is recommended to limit whey protein or replace whey with other sources, such as pea, rice or vegetable protein supplements. You can also consume vegetables, fruits, pulses and cereals and avoid excessive consumption of poultry and meat to make sure that you get all the essential amino acids .