Full low carb, to me, is a diet that severely restricts carbohydrates, cutting out grains and fruit, and limiting starchy vegetables, instead eating mainly protein and fat.
A low-carb diet limits carbohydrates — such as those found in grains, starchy vegetables and fruit — and emphasizes foods high in protein and fat. Many types of low-carb diets exist. Each diet has varying restrictions on the types and amounts of carbohydrates you can eat.
www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/low-carb-diet/art-20045831
A short term (2-4 months) very low carb diet may be useful to kick start weight loss but could be risky in the long term or if carried to extreme. I'm all in favour of eating mostly lean proteins but would not ever restrict intake of vegetables. A moderate amount of unrefined carbs and healthy fats such as olive oil are essential for energy and balance.
While short-term carbohydrate restriction over a period of a week can result in a significant loss of weight (albeit mostly from water and glycogen stores), of serious concern is what potential exists for the following of this type of eating plan for longer periods of months to years. Complications such as heart arrhythmias, cardiac contractile function impairment, sudden death, osteoporosis, kidney damage, increased cancer risk, impairment of physical activity and lipid abnormalities can all be linked to long-term restriction of carbohydrates in the diet.
pubmed.ncbi.nlm.nih.gov/14672862/
Diabetics and people with cardiovascular and renal disease have to be extra careful, which is why getting some blood work done is advisable if one is contemplating a very low carb diet.