Generally we always try and consume most of the calories for the day at night for several reasons but sometimes you won't have that option or you will need to break your fast earlier than usual.
There are ways to make up for it with little impact on your days results.
Firstly is it's just food timing and the first meal is simply eaten earlier you just need to think about how much energy you are putting into that meal and the time you have before the next meal.
With the first meal we only want energy for up to 3hrs so we can fit in some fat loss before the last meal.
With the last meal we have a longer fast until the next days first meal so you need more calories for a better metabolism.
If are thinking of avoiding carbs with the first meal remember that you will still raise insulin with protein so you will still lose 3 hrs or so of fat loss even without the carbs and some of the protein (up to 50%) will convert into energy as your liver glycogen (blood sugars) will be low.
A perfect first meal, regardless of what time it is consumed, should contain only 20-30g of carbs or less (taken off your days quota) with a small amount of protein and as little fat as possible.
If consuming bread then make sure you allow for the extra carbs in the other food and if the protein amount is more than 20g then also allow for the possibility of some of the amino acids converting into energy, just like fats do when needed.
A single slice of bread with a couple of pouched eggs is perfect or a ham and salad 7 grain sandwich (thin sliced bread).
The first meal choice has more protein and fats so the carbs are less, meal choice two has only a small amount of added protein (bread had protein also) as well as less fats so you can add carrots, beetroot, a small amount of mayo, chutney etc.
If the meal above was consumed even at 8am in the morning you would only effectively be breaking your fast for 3-4 hrs so you will continue to lose stored fat after this time until your next meal which will hopefully be your evening meal.
As an example - 8am till 6pm equals 10hrs
An 8am meal like the meals mentioned above (30g carbs and a small amount of fat and protein) will break that 10hr time by 3-4 hours due to the energy in that meal so if you can resist the early meal cravings (why we generally avoid the early meal) you would be fasting for 6 hrs before dinner (from 8am).
A 1pm identical meal (30g carbs and a small amount of fat and protein) will break that 10hr time by 3-4 hours also, due to the energy in the meal. You will likely still get some post meal (low blood sugar after insulin response) cravings but it would be so close to dinner time that it will be easy to avoid.
The total time of fasting(from 8am) would be the same.
Where it does make the difference is obviously what you eat both the night before (how fast your metabolism is) and with your first meal.
The early meal for some people who can resist the post meal cravings and the lack of energy that comes with the blood sugar drop may boost metabolism slightly more, especially if they are overactive.
Research has proven that your metabolism does not slow down for up to 40hrs after a meal (up to a 9% loss was found) but exercise can slow down metabolism overnight as your body is designed to survive and therefor limits energy use if calories are low.
Another time an early first meal (only for those who can avoid the cravings) can be beneficial is after a long fast such as on a Tuesday morning to help boost metabolism. This is generally only beneficial for those who do not have large or higher calorie 'Free Day' meals.
If you ate a whole pizza to yourself you should generally have a very fat metabolism right up until Tuesday night if needed.
Cravings can be reduced by choosing slower digesting foods (more grains etc) and by adding more fats to the meal.
Everyone has different insulin sensitivity though which is a major factor of blood sugar control which causes the cravings and lack of energy.
With a more indulgent first meal you would get the following energy supply -
2 eggs (energy for 1-2 hours), half an Avocado (energy for over 2 hours), a lean slice of ham or bacon (energy for 1-2 hours) and 2 slices of standard toast (50g of carbs, energy for 5 hrs).
That's over 10hrs of energy instead of the 3 hours we aim for the first meal.
If you were an athlete that would be perfect however for fat loss the extra exercise will effect future fat loss and make weight maintenance a lot harder in the future.
The above meal would not be an issue if consumed within your 6-8 hour recommended eating window as part of your daily calories (carb total mainly).
Best thing you can do with the follow up to a meal like this (or larger) is to skip all other meals and snacks until dinner.
The meal is actually unlikely to store any fat if your body has room for the carbs and any fat stored from excess consumed fats will likely be used up with the overnight fast.
The metabolism boost may also help speed up fat loss slightly but it is unlikely that you will get the same results as proper dieting due to the loss of fasting hours with the amount of energy consumed feeding your body when blood sugar levels are low (from your liver).
Your liver holds up to 10hrs of energy supply for your blood stream.
While there is an energy supply in your liver, fats cells will not be broken down into energy (no fat loss).
The majority of the energy in the foods you consume goes straight to your liver after blood sugar levels are raised and then any excess is sent to your muscles after your liver is full (fat cells if muscles are also full).
Fructose (fruit, corn, 50% of sugar) however is rejected by muscles so after your liver is full it all goes to fat cells.
The only time you can try and get some of the carbs to your muscles when your liver is not full (to empty your liver earlier while still getting the metabolism benefits for more fat loss) is post training with heavy weights.
Your muscles request the amino acids (protein) in your blood stream for repair and take-up glucose (carbs) at the same time with the insulin response.
So a good time to workout with weights is just before a meal.