Ok, I’ll give you some personal thoughts.
I want to disclose this saying that there are plenty of people doing low carb diets and even lower carb diets (keto).
Despite that, I would personally not go 100% on Black. Do I think you will encounter any health issues? Most likely not. As long as you keep your calories within your needs, Huel should offer you a balanced nutritional input. So why the negative take?
- The macronutrient split is even further from what the government agencies recommend. 20C/40P/40F (% of the energy from).
“General dietary guidelines for adults suggest an acceptable macronutrient distribution range (AMDR) of 45-65% of total energy from carbohydrates (CHO), 20-35% from fat (F), and 10-35% from protein § with a recommended dietary allowance (RDA) of 46 and 56 g/d or 0.8 g/kg body weight (BW) of P for females and males, respectively”
- Protein content is extremely high. At 200g of protein a day (for 2,000kcal), that would mean that a person weighting 80kg would have 2.5g of protein per kg of bodyweight. To put into prespective the recommended to maintain muscle mass is 0.8g/kg and to build between 1.6g and 2.2g. Extreme high protein diets, while beneficial for weight loss in the short term, might cause some increase in your kidneys. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4258944/
- Protein is not the most efficient form for your body to take energy from. Carbohydrates are getting a “bad name” in an era where sugars and processed carbs are everywhere. These when paired with unbalanced diets and caloric overloads cause obesity, diabetes etc. However, carbs are the most primary source of energy. Long term low carbohydrate diets are not as well supported and studied.
And then there are the concerns when going 100% on a meal replacement diet. Again, it has been done multiple times, mostly successfully by other members of the community. However, evidence of long term benefits or harm is non-existent.
So, if you keep track of you health, you don’t notice any energy issues, etc. I think that you should be fine. It’s not going to kill you, and likely it will not harm you.