This is a loaded question, it seems simple but in fact it is quite difficult to answer. There is one part of a low carb diet missing here...the vegetables. Where are the vegetables? A low-carb diet a vegetable diet with meat added to it. That being said meat is not a core component of a low carb diet, it is more of a want or comfort food for many people who gravitate toward a low carb diet.
Protein is a macro-nutrient needed for the body to access essential amino acids it cannot make by itself. Amino Acids are needed for DNA production and synthesis, messenger RNA production and synthesis, just to name a few of the various functions within the body. However, there are other sources of essential amino acids such as legumes, eggs, dairy products, animal proteins, grains, nuts, and even some vegetables. Long story short it is important have adequate amounts proteins but not so much that it needs to be the heart of a diet. In fact if protein is too predominate in an individuals diet it can cause more harm than good. Current research suggests excessive protein intake over long periods of time with increased cancer risk and kidney complications. New research suggests adults only need to consume 0.6g protein/kg for optimal function. However, most Americans consume 1-1.5g protein/kg despite the current recommendations of 0.8 to 1g/kg for adults. OK now that there is a simple background understanding lets dig into the issues with too much protein while following a low carb diet. While following a low carb diet an individual will notice a drop in weight and blood sugars,for diabetics and/or pre-diabetics, if protein is high weight loss will stall. That's right you'll lose weight then boom stalled and not moving. What tends to happen is protein is used as a secondary fuel source to turn the Kreb Cycle, an energy production wheel. This means you will no longer be fueling from fat as efficiently as you should be. Even more the breakdown of the glucose stores from glycogen is no longer happening as efficiently as it should be. Access protein is utilized for energy. Knowing that protein can stall weight loss do you see why I push vegetables? Vegetables need to be the heart of you diet for long-term sustainable success. That means keeping protein to a range of 0.6-1g protein/kg body weight. For most of us this means 4-6 of protein 2-3x/day. Here's an example of how to determine your protein needs: an individual who is 250 lbs. 1st convert to kilo grams(250 lbs. * 0.453=113.25kg) now multiply to get grams of protein needed (113.25*0.6g protein=67.95g protein/kg...lets round up to 68g/k: 113.25*1g protein=113.25g protein/kg) this is a range of 68g protein to 113g protein. That's a big range but it gives you some flexibility and a more exact way to regulate protein needs.
Alright now that the protein makes a bit more sense lets dive into the fat piece. Fat is another macro-nutrient the body needs for absorption and lots of other everyday functions including an energy delivery service for the body. But fat can be over done as well. The nice thing is that our body will self regulate fat intake as long as we listen to it. Fat is a satiating macro-nutrient meaning it makes you feel full. If you over eat, eating past that feeling of full, then you are taking in more food than you body needs. If you take in enough fat eventually that will hinder weight loss because there are enough calories coming in supporting your current body weight. The key component to fat intake is not hitting a particular amount but rather eating enough fat to feel satiated, recognizing that point of fullness and stopping there. This does not mean drinking bullet proof coffee several times per day or eating fat bombs throughout the day. There is no particular amount of fat I will suggest as a general since there are lots of variables that can effect an individual's needs. I suggest keep it simple don't avoid the fat in your food, use satiety to determine portion size and amount of fat needed, and do not go out of your way to add lots of additional fat to your diet.