As with many restrictive diets, low-carb diets do work.., at least in the short-term (see more later). However, whilst safe overall, one should seek medical guidance if diabetic and eat more carbs on work-out days and be especially mindful not to go so low you trigger headaches and hypoglycaemia.
Besides losing weight, low-carb diets have been shown to reduce blood pressure and blood sugar levels. Moreover, a high % of the fat is lost around the belly area and liver so excellent for those with metabolic disease.
Why these diets work is a bit more controversial. Possible ideas:
1. Carb restriction drastically lowers blood insulin levels. Insulin regulates blood sugar levels, promotes fat storage and prevents fat burning. Low carb diets therefore mean lower insulin levels and so the fat can be used. Advocates include the Atkins diet.
2. High water loss in the first 1-2 weeks occurs with people of low carb diets. This is due to lower insulin levels, which result in sodium secretion and also, glycogen breakdown, which occurs to provide energy.
3. Increased protein intake. By eating less carbs, you naturally increase the intake of protein. Many studies have shown that protein helps to reduce appetite by promoting the feeling of ‘fullness,’ boosts metabolism and helps to increase muscle mass,which in turn burns more calories.
4. Very low carb diets promotes ketogenesis i.e. when protein is converted into glucose (gluconeogenesis). This metabolic process is inefficient and so many calories are ‘wasted’. However, this effect is temporary.
5. Low carb diets help you to feel fuller and so it is easier to make healthy choices and you tend to eat less overall. This may be through the effect of low carb diets on appetite hormones leptin and ghrelin. (Hence following the ‘calories in and calories out’ model).
6. No sugar spikes and dips. Low carb diets also mean that many high calorie foods, which cause sugar spikes and consequent hunger pangs (as blood sugar levels dip), are avoided. A high protein diet means that blood sugar levels are steadier and so it is easier to make healthier dietary choices.
However, one thing to note: while low carb diets are effective in the short-term, the long-term results are not brilliant. This may be because people abandon the diet.
Overall I would advocate a healthy lifestyle; eating clean, exercising, limit alcohol, drinking plenty of water, getting enough sleep, reducing sugar intake rather than any particular exclusion diet.