If you're like me, you've probably already done a ton of research. You've read the same tips over and over again, the same generic advise that should do the trick for everyone.
The problem is that everyone is different. This is not a scientific article with research to back it up. It's a report on my own personal case study. My best tip is to experiment with what works for you!
I'm currently on vacation, and I'm so proud with how hard I worked to look this lean!
I've been working out for about 3 years now (weightlifting for 2) and have never seen this much progress in my body. In January, I really kicked my training up a notch, both because of the New Year and some personal motivation. It started off with a bulk. I was lifting heavy and eating in a surplus. It was great! I gained 10 pounds, which is a LOT for someone who typically floats between 108-115. I mostly put on muscle, but a little fat as well. I did hardly any ab workouts and little cardio, but during my heavy lifts I really focused on engaging my core.
My lifts got heavier, and I packed on muscle. I was eating clean, with a focus on lean meats, veggies, fruit, whole grains, and healthy fats, with some simple carbs thrown in for my own happiness (ie white bread, my favorite thing in the world).
Around mid-March, I decided to slowly shift gears into a cut, which means I wanted to burn more calories then I was taking in. Please note the emphasis on "slowly." A lot of people tend to try to do everything all at once: adding in exorbitant amounts of cardio and cutting calories to the point where your body can hardly function. Don't do that, please. Your body will go in starvation mode, and you'll probably hate your life.
Workouts
Instead, I started slowly increasing my cardio without touching my food too much. As the New England weather started to unpredictably get better, I started going for longer and longer outdoor runs. Running is my favorite cardio, but don't feel like you have to run. There are so many other types of cardio, which I talk about here.
Cardio will help you to burn more calories and be in more of a calorie deficit. Being in a calorie deficit will help you drop fat (and unfortunately some muscle) throughout your whole body. You can't spot reduce. For me, I lose weight on my limbs fast. My stomach, butt, and upper thighs hold onto weight, while my arms, shoulders, and even my lower thighs drop weight pretty fast. Everyone is different, and if you lose weight on your stomach faster, then you'll get abs faster.
When I started the cut, I was hardly doing any cardio. I was maybe running a mile or two on the treadmill and doing HIIT workouts once or twice a week. I was hardly doing any Low Intensity Steady State Cardio.
Since I started the cut, I really amped up the amount and intensity of my cardio. Before or after every strength workout, I would do cardio for 10-15 minutes, with two days a week dedicated to full cardio workouts. I was still strength training, and I was still lifting heavy to try and maintain as much muscle as possible. Unfortunately, when you're doing a lot of cardio and eating in a deficit, it's easy to lose muscle along with the fat.
Food
Increasing your cardio is also going to increase your appetite, which is why if you cut your food at the same time you add in more cardio, you will be starving 24/7. After a couple weeks of increased cardio, I started to decrease my food, between 100-200 calories a week. I use LifeSum, a calorie tracking app to track my macros and calories. I'm terrible at estimating portion sizes, but it was still really helpful to get a good idea of what I was eating.
Since January, I've been on a high-protein diet. Starting in April, I (again slowly) starting cutting my carbs. I completely cut out gluten, and already wasn't eating dairy, processed foods, or sugary foods. You would not believe how much those make me bloat, and they're probably making you bloat as well.
For reference, I was aiming to eat 152 grams of protein, 62 grams of fat, and 55 grams of carbs, although everyone is different. I don't think I ever successfully ate 152 grams of protein anyway. In mid-April, for breakfast I was eating a bowl of oatmeal with strawberries, a banana, and two table spoons of nut butter along with a protein shake. For lunch I would have a serving and a half of chicken with half a cup of vegetable fried rice and mixed veggies topped with some sweet Thai chili sauce. Dinner was incredibly inconsistent, but I'll tell you that one of my favorite dinners was a bowl from Moe's with steak, black beans, guac, pico de gallo, cucumbers, mushrooms, and olives. I also probably ate sushi 3 times a week, but I don't recommend that. That was probably around 1700 calories (which is probably a 200-300 calorie deficit depending on what I do).
Each week, I changed my diet to include less carbs and less calories. This past week (right before my vacation!), for breakfast I ate half a serving of oatmeal with strawberries and nut butter with a protein shake. For lunch I had chicken with veggies (no rice). For dinner, I was eating a serving of fish with veggies. That was around 1500 calories, which is low for me.
I don't recommend cutting carbs this extremely for a long period of time. I only did it to reduce bloat for my vacation. It had a negative impact on my workouts and mood.
Ab Workouts
My ab workouts were relatively simple for the first few weeks:
Circuit
15 pike on TRX
15 saw on TRX
15 chest ups with 16 pound med ball
30 Russian twists with 16 pound med ball
30 rotating planks
15 reverse crunches
15 leg lifts holding 16 pound med ball above my chest
15 jackhammers with 16 pound med ball
That ab circuit left me with my abs burning every time. Just like any other muscle, if you want to grow it, you have to increase the intensity.
The last 3 weeks before I left for vacation, I switched up my ab workout completely. Instead of doing circuits, I did 60 reps of each move with rest in between and breaks when needed (looking at you TRX pike and TRX saw).
Take Away
Please don't hate me for saying this, but the biggest thing I learned this past few months is that consistency is key. I was working out 5 times a week and eating healthy about 80% of the time. This was a really fun experiment for me, and I'm glad I got to understand my body a bit better.
I recommend following my process: bulk and gradual cut. I'm excited now to follow this process in the future but for longer amounts of time.
Throughout this whole process, I really focused on eating mostly clean food, which is SO important. It's probably the most important thing. If you aren't seeing any changes, I recommend cleaning up your diet. Cutting out gluten, dairy, processed foods, and sugary foods/drinks made a huge difference after a few weeks.