What is a diet?
Diet´s are by definition a meal plan or a nutritional plan that includes more or less calories per day than what you consume. In order to lose weight, a person would have to eat less calories than what he/she consumes in a day. There are so many misconceptions on how diets should be structured. Some say that you can´t eat any sugar or "bad" carbs while others may think that you can eat whatever you want as long as you stay at a caloric deficit.
Starting a diet
The first thing everyone should do when thinking of a diet is tracking what they eat for 3-4 days. From that you know how many calories (protein, carbs and fat) you are currently consuming. Knowing your current level you know what amount of calories equals your current bodyweight. Most of the clients I see are eating way too little, whether it´s a man or a woman, and the calories are around 1500-2000kcal/day. Some go for the upper limits hitting nearly 4000-5000kcal/day.
Now if you think about it, 1500kcal is too little for any person to start the diet. Are you going to take out 300kcal and manage with 1200kcal? The answer is no. A human body requires more calories to maintain its natural functions and hormone levels. So if you are currently eating too little, you first need to make your body adapt to eating more while still maintaining the same weight. More on how to do this later.
If you´re eating 4000+kcal, it´s easy to cut off some. Your body is already consuming big amounts of calories and has lots of room to decrease. Diets are really not that complicated so don´t overthink it!
Example from my personal journey
As a 6'4 male I was at a point where I trained for 4-5 times a week and consumed 5000kcal per day. My weight was around 240lbs while having a fat percentage of 22. I started decreasing my calories and lost 50lbs within 6 months ending up at 1900kcal/per day. The reductions were 500kcal less every week or every two weeks, mostly reducing carbs and keeping fat and proteins constant. After reaching 1900kcal I was so weak... My body started breaking apart and I needed to start upping my calories.
Four years later I was eating around 2400kcal and weighing 235lbs and holding a lot of fat again. How is this possible? Shouldn´t I be significantly less if I´m only eating 2400kcal and training often? NO! I had my body used to eating only 2400kcal while maintaining a high bodyfat. I did that by letting my body and metabolism shut down which resulted in me just getting fatter instead of losing weight.
How did I overcome this?
I started adding 200kcal every week (only adding carbs). Soon I noticed I was either losing some weight or maintaining my current weight even though I was eating more every week! This was only due to my metabolism starting up again. If you think about it, a man who is 235lbs should eat around 4000kcal to maintain that weight, but I was maintaining it with only 2400kcal. Starting a diet from those stats would´ve been impossible as I would have not lost any weight and only harmed my body more.
As a result, I got back up to 3400kcal and ending up with that same 235 lbs that I started with. Now my body was again used to 3400kcal per day with the weight of 235lbs. I was ready to start my diet.
Constructing a consistent diet
A diet shouldn´t be something you do when you get fat and try to get in shape quickly. It should be a lasting change in your eating habits that is easy to maintain. You aren´t going to maintain a salad only, no carbs, no fast food diet for the rest of your life. You will end up binge eating and going through periods where you just pig out and forget about trying to lose weight.
Instead, allow yourself to eat sweets, pizza, hamburgers and whatever you want. "Wait what? This is BS!!!". Now hold your horses. I didn´t say you can eat as much as you want all the time. Everything needs to be in moderation. If you divide your day into 4 meals while eating 2400kcal it would mean 600kcal per meal. Your protein should be around 30%, carbs 50% and fats 20% (this will vary on individual basis). So for every meal you have 300kcal that come from carbs. Out of that 300kcal, 20% can come from sugars (Ice cream, candy, chocolate etc.) So with every meal you can eat 60kcal worth of sweets or at the end of a day, eat 240kcal worth of candy in this example. See how simple it is?
If you eat 4 meals per day, you´re eating 28 meals per week. It´s okay to screw up 2-4 meals during a week as long as it´s not by a huge amount (like eating 10 big macs on one meal). It´s not going to make a big difference in your diet. We use a certain meal plan to support a healthy lifestyle, not to make us super thin in a way where we can´t train or function normally anymore. You should enjoy your life and not have to starve. Denying something will you only make you want it more. Instead, eat sugars or fast food, but keep it in check!
Role of exercising during a diet
Weight loss is based on a caloric deficit so excercising is not a must! YOU CAN LOSE WEIGHT BY ONLY EATING LESS. Is this ideal? Ofc not. I would always say that you need to excercise to keep up your metabolism and tone your muscles so that you burn fat more efficiently. If you want to argue that you always need to workout to lose weight/fat, then how are people at hospitals losing weight? It´s because they eat so little.
When coming up with a workout plan, don´t overdo it. The goal is that you can maintain your current activity level even with lower calories at the end of your diet. I see so many people starting with 90min of cardio 4 times a week and working out with weights 3 times a week... how are you going to keep that up with 1/2 of the calories 3 months from now? You can´t progress that way. Or will you do 180min of cardio 6 times a week and train with weights for 5 times a week? I doubt.
Start slowly and build up little by little. Personally I don´t even do cardio on my diet. I just workout with weights and eat as instructed. I don´t go back on my workouts, I always try to get stronger and make the workouts tougher. I eat ice cream every night. I eat pizza every week and I drink a beer or two every week. If I wanted to fasten the diet, I could add cardio, but that wouldn´t be ideal as I want to maintain my muscle mass as long as possible. If I want to lose more weight, I´ll just reduce 30g of carbs from my diet until my body loses a little weight and again stabilizes. If I want to add weight, I´ll add 30g of carbs until my body gets used to that addition. All without adding fat to my body.
Step-by-step guide to dieting
1. Track your calories with an app like MyFitnesspal or similar for 3-4 days
2. Deduce your daily activity level - If you just sit around all day, you might need to walk for 1 hour per week just to increase your basic activity level to normal
3. Decide whether you want to lose or gain weight
4. Find out if you´re eating too little for your current weight? If you are, start by increasing your calories little by little until you get to higher levels. Then you can start dieting
5. Set up a meal plan. 3-5 meals per day according to your schedule. 20% of carbs can be from sugars!
6. Incorporate a workout plan. Start slowly! This is a process that hopefully lasts a lifetime. If you don´t workout currently, start with something very doable like working out 2 times per week for 30min. Next week you can increase it to 2 times and 40min etc. DON´T both increase your activity and reduce calories. This will be too much of a change. You want to have as much leeway as possible for the whole duration of your diet.
7. Take your time with weight changes. Let your body stabilize to a new level after reducing or adding calories before you add more or reduce more. 3 days without weight fluctuation would be ideal. If you feel really hungry all the time, take a step back and add some more carbs. Diets are really not that hard if you do it properly. If you decide that you want to workout more, let your body get used to that new level of activity without changing your calories. (Think of a math problem: It´s much easier to measure changes in outcome if you only change one variable. If you change two at the same time, it will get trickier and harder to know which variable caused a bigger change)
8. Take time off from gym when you feel very tired. This means that your body is closing in on overtraining. 3-4 days of followed by 1 week of light training will get you back on track. Keep up with your nutrition even during this time. No changes in that!
9. Consult a PT or some other person who has experience with this! If you struggle, a professional will help you a lot and you will save money + time in the long run.
For all who doubt what I´m saying, the principles are based on experience and multiple scientific studies. I have a pt and I´m a bodybuilder. The diet method I follow is "IIFYM" or If It Fits Your Macros. I´ve been doing this for 8 years and have tried it all.
Good luck and enjoy the start of your new healthy life!