Are low carb caloric needs the same as suggested with a high carb diet. In other words on a low carb can I trust the total daily calories suggested by tracker like 'my fitness pal" or "lose it"
I wouldn't trust the daily calories from any such site in any event, but yes - your caloric requirements will vary depending on what you're eating. You'll probably burn fewer calories on a low carb diet. It's a fool's errand though trying to calculate it all. Your body is constantly trying to rig the result.
Calorie requirements and carb intake are not related. I assume most calorie trackers use the Harris-Benedict formula, which multiplies BMR by an activity factor to estimate daily caloric needs. There is no provision in that for macronutrient ratios, nor should there be.
Carbs are 4kcals/gram, while fats are 9kcals/gram, so if you do go low-carb, you may find that you meet your calorie needs faster or with eating less than a moderate- or high-carb diet.
Your calorie needs are determined experientally and the sites only provide general guidelines. I personally found them to be pretty accurate over a wide macrontrient range when I was losing 2 lbs a week, but I wasn't ever using VLC or ketosis to lose that weight.
Remember the energy expenditure side too. I'm doubtful that low carb affects calorie burn rates for exercise but it might.
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