IN MY OPINION consult you’re doctor before you start
A lot depends why you’re losing weight health, cosmetic shidduchim etc.
It also depends how much you are overweight and need to lose.
I offer the following suggestions
1. do this under the care of your physician see him/her before you start, talk it over and perhaps you may want to go back during and after you lose your desired weight.
2. You must have a partner, a person close to you on board, you can’t do this alone. Your spouse/parent/roomate etc. must be there to support you, help, and give encouragement.
3. Dieting is expensive and takes time. You need to buy and eat certain foods that might cost more than you usually spend, they need to be prepared properly to make them enjoyable to eat, and you need to eat at the appropriate time and pace. You also need to take the time to excercise consistently.
4. Do not drink soda perion only setzer or water, do not eat after 7:00PM only soup or drink, take the time to eat three healthy meals a day, try to eat five fruits a day, drink a cup of dry red wine a day, only whole wheat bread or pasta and only one meal a day, no cake, candy, Pick one day a month to cheat usually rosh chodesh but then fast in the morning to cleanse your system and go back on the diet. eat before you go to a simcha at night and then tell the bal simcha not to set you a place but you’re coming to share their simcha Fish is very healthy as well as chicken. Do not mix carbs with protien as much as you can. If you like pizza eat two slices for an ealy supper and then nothing till the next morning. If you go to a kiddush don’t eat, remember you have healthy food at home that will fill you up. If you need a snack keep enticing looking fruit available for impulse eating. Shabbos eat whole wheat one slice, 2 bowl of chicken soup leaas everything else, salmon or white fish instead of gefilte, and limit the kugels.
good luck