So you've started a new diet - things are going well - but you are finding that by the evening of day 2 you are feeling pretty hungry (which tends to happen when you really restrict your food intake)... and then you get home ...
and suddenly you think - "this vegan diet is silly anyway - I have heard lots of information that it can cause B12 deficiency" - or "this keto diet is ridiculous - our body needs glucose to survive" - or "being paleo isn't good for you - grains like oats are important for our gut health" ....basically your brain finds any information it can to support the idea that your new diet is a waste of time and that you should give it up - eat EVERYTHING you want to this evening - before starting another new diet TOMORROW.
This is confirmation bias - we find evidence to support whatever it is that we want to believe in that moment. So in that moment that you are physically very hungry your brain will find any evidence it can to confirm that what you are doing is BAD and WRONG for your body - really just so you can give yourself permission to eat.
This is why, if you want to embark on any new lifestyle - you have to make sure that it does not also involve starving yourself/skipping meals or going hungry. If you try to go vegan or paleo but are also counting calories and restricting food - there is a good chance eventually your brain will find evidence that what you are doing isn't good for you - because it is allowing you to go hungry and feel deprived. It also helps - when embarking on any new diet or lifestyle, to give yourself some flexibility - so don't immediately aim to go 100% vegan or 100% paleo - allow yourself sometimes to eat other foods - so that you don't feel deprived and ever feel the need to justify bingeing on those foods.
Over-restriction is one of the biggest drivers or binge-eating and over-eating - so stop the diets, stop obsessing over the scales ...and you will begin to notice that your body just knows what is best for you.
“Get off the scale! I have yet to see a scale that can tell you how enchanting your eyes are. I have yet to see a scale that can show you how wonderful your hair looks when the sun shines its glorious rays on it. I have yet to see a scale that can thank you for your compassion, sense of humour, and contagious smile. Get off the scale because I have yet to see one that can admire you for your perseverance when challenged in life.” – Steve Maraboli