from wikipedia
Each meal provides about 1,200 Calories ....
Each MRE weighs 18 to 26 oz.
There is a lot of confusion regarding MREs in many of the Prepper BOB youtube videos. Many think that a single MRE per day per person is sufficient. There are even some who think even 2 MREs will be sufficient for two people for 3 days when bugging out. These folks are suffering from MUSH thinking.
25 miles per day Tabing is exceptionally good going whilst carrying more than 30-40lbs pack loads. Calorie requirements could be as high as 5000-6000 Calories per day i.e. 4-5 MREs i.e. 7-8 lbs. A British 24hr ORP weighs around 1.7kg 3.75 lbs and has around 4000-4500 Kcal.
To improve range a Bicycle with panniers and or trailer will help considerably. Mark Beaumont would typically cover 100+ miles per day carrying 60lb loads during his record breaking cycle around the world attempt. Again 5000-6000 calories was required. There is also a limit to the amount of edible calories that can be consumed by the body. Typically 6000-7000 calories. This is why Tour de France riders will lose weight in Mountain stages no matter how much they ate.
Making your own Ration packs can be more efficient (Energy Density) for conditions where water is readily available.
Ainsley Harriot Wild Mushroom Risotto 120gms 566Kcal
Salmon Fillet in Mustard and Dill Sauce 190gms 350Kcal
Knorr Thick Vegetable Soup 75gms 260Kcal
PhD Flapjack 75gms 286Kcal
PhD Flapjack 75gms 286Kcal
SIS Go Energy Bar 65gms 217Kcal
Fin Carre Dark Chocolate 100gms 524Kcal
Paterson Shortbread Fingers 180gms 900Kcal
Travel Lunch Mousse au Chocolate 100gms 411Kcal
Expedition Foods Beef Curry with Rice 162gms 915Kcal
Total Weight is around 2.5 lbs and has 4700 Kcal. This would be twice the energy density compared to an MRE.
The ability to travel 400 miles using a bicycle (assuming 80 miles per day - 6-8 Hrs pedaling a day) could be achieved with 5 of the above ration packs i.e. around 6kg or 13.5 lbs of food. Having the ability to carry 25+ lbs of gear is quite doable using a bicycle and trailer. The BOB Ibex trailer is rated for 70lbs. Walking/marching/tabbing self contained with MREs probably wouldn't get you more than 120 miles before running out of food.