Three things for you.
1- Where did we get (in our society) the idea that we need to "cleanse" before we start a diet. It really isn't necessary, just start changing your eating habits and activity habits. Eat healthy, lots of fruits and veggies and whole grains for all the fiber (legumes are great too!) and your digestive tract will constantly and gently cleanse itself out.
2- Don't go "on a diet". Change your diet (the word originally meant lifesstyle, specifically eating habits). You want to make changes you can follow pretty well for life, or you'll just end up gaining that weight back, which is bad for your health (gaining, loosing, gaining, loosing - not good). Weight is simply a law of thermodynamics. Meaning calories in vs calories out. If in is more that out, it will be stored as fat. If out is more than in, the difference will be made up by burning fat. Best way is to increase out (by excercising both cardio and muscle - muscle burns more calories even at rest) and reducing in by eating fewer calories. Fill up on veggies. They are yummy, there's a huge variety, they're full of vitamins and fiber, so you feel full. Also, eat whole grains instead of refined (whole wheat bread, brown rice, etc). Fruit makes a great desert. Don't cut out the carbs, protein, or fat all the way - our body needs all 3, and it doesn't really help. Just reduce the amount by eating healthy and watching your portions. (When I was loosing weight I tracked my calories daily. I kept a quart of really good ice cream in the freezer, and if my calories at the end of the day were low enough, I had 1/4 to 1/2 cup ice cream - measured - that I ate very slowly, to treat myself for a good eating day.)
3- Don't be disappointed if you don't loose all the weight this year. Expect to loose maybe 3 to 5 pounds a week - and that's if you're really careful about what you eat and exercise 5 days a week (1/2 to 1 hr a day at most). And it will slow down as you get closer to your goal. It's not healthy to loose a lot faster than that, and you'll be more likely to regain it later. Remember, you're changing your eating habits and lifestyle to be healthier, not just dropping pounds. So plan on maybe 50 lbs this year and then 25 next year - if you're really disciplined. After all, I bet it took you more than 1 year to put on the weight, it will take more than 1 year to get rid of it.
Good luck! You CAN do it!!