You have two things you want to accomplish,
I) To reduce your Belly Fat
II) To get your abs Stronger
And you would like to know how, doing Planks might help you attain the above goals.
First, to address the issue of Planks. Form is very important with Planks (as they are with any exercise, for that matter). So, you need to learn what the correct forms are, and will need to maintain that throughout your set.
Also, there are some variations of Planks (such as RKC Planks) that are harder and more effective than the “usual” version of Planks.
Again, knowing and maintaining correct form in any version is most important, as discussed above.
Although doing Planks are undoubtedly better than doing nothing at all (some activity is WAY better than no activity), there are far better ways to attain both your goals.
Reducing Belly Fat:
To reduce your Belly Fat, the most important is Nutrition. You need to eat the right kinds of food, in the right quantities, at the right times.
Below, I am cutting and pasting from one of my answers to a similar question, elsewhere on Quora
The MOST important factor that determines how much fat you will lose and how soon, will depend upon your NUTRITION. No amount of Exercise, whatever the exercise maybe, will compensate UnHealthy Food Habits. You cannot out exercise, bad diets.
So, do not worry about the treadmill (although, exercising will help, but again, as mentioned above, NUTRITION is the MOST IMPORTANT factor).
If you have significant Belly Fat at the moment, then, for sure you are Insulin Resistant, perhaps pre-diabetic or even Diabetic. In case you have not done so already, please visit your Doctor and get tested for Diabetes.
Towards changing your Nutritional intake, you could Reduce your Daily Calorie Intake, and of course, increase your activity (Exercise and non-Exercise activities) to Increase Calorie Output. You could also Change your Food (Macro) Composition.
My suggestions are:
- Eliminate Sugary Drinks altogether (Soft Drinks, Juices…anything with Sugar)
- Eliminate simple Carbohydrates (Rice, Wheat, Bread…and all related food items)
- Eliminate Starchy “Vegetables” such as Potato
- Eat more Vegetables and Greens
- Eat more Complex Carbohydrates (such as Oats)
- Eat Protein with ALL your Meals (Good Quality Protein)
- Eating Fat is Good for you,
- All Fat except Trans Fat are good to eat.
- However, Fat is VERY Dense Nutritionally…you could overeat fat easily (and quickly add a lot to your Calorie Intake). So, watch out.
- Fat is pretty Satiating though, so that is a HUGE positive.
- Fat does not Increase Insulin Levels significantly, if at all… This is yet another HUGE positive.
- Reduce your Stress Levels. While avoiding Stress in impossible, you can control your reactions to stress. Be Cool…do NOT stress out. Especially, ensure that you are not Stressed Out ALL the time.
- Give yourself 4-5 hours gap between meals. Do NOT snack (at all) in-between meals.
- Eat your Dinner as early as possible in the evening. Give a gap of 10-12-16 hours gap between Dinner and Breakfast the next morning.
- In addition to all the above, you could try Intermittent Fasting (or even Extended Fasting).
- This will give you results much more quickly.
- However, don’t jump into an extended fast right away. You will need to work your way slowly towards increasing your Fasting times.
- If you go on Extended Fasts then, stay hydrated, keep up with your Electrolytes intake.
- When the Fasting ends and you start Re-Feeding, don’t splurge on the food. Take it slow…and, go easy with the Carbohydrates.
- Be very sure that if you are Diabetic and on Medications/Insulin Injections, to test your Blood Sugar levels with any changes to your Diet/Exercise/Activities. Ensure that you do not get into a Hypo Glycemic (Low Blood Sugar) state, which could be fatal.
Any/all the above, will help you reduce Belly Fat.
Getting you Abs Stronger:
Regarding your Second Goal of Getting your Abs Stronger, rather than Body Split exercises, whole body exercises such as the Squat, Deadlift, Press and to a smaller extent, the Bench Press, will help in getting your Abs, as well as your whole body, Stronger.
Again, as mentioned above, for any Exercise, you should learn the proper form and should maintain proper form through all your Reps and Sets.
Moreover, you will need a proper and appropriate Training Program, that will contain details such as Which of these Exercises to do, When to do Them, the Weights to be Used, the Number of Sets and Reps to perform etc., as well as the way to implement Progression on all these aspects.
A QUALIFIED Coach, will go a LONG way to get you going in the Right Path.
None of the above should be construed as Medical advice. Please visit your Doctor and/or Nutritionist before making any Sudden (and Drastic) changes to your Medication (in fact any change to your Medication should be approved by your Doctor), your Nutrition and to your Activity Levels.