By Eleanor Bradford
BBC Scotland health correspondent
Bride-to-be Lisa Jane has followed a Weightwatchers diet
It's my final visit to see slimmers Lisa Jane Laurie and Lyndsay McIntyre.
They're both dieting for Lisa Jane's wedding in July.
Since I met her in January bride-to-be Lisa Jane has lost just over 1st. Bridesmaid Lyndsay has lost nearly 3st.
Lisa Jane, who followed a Weightwatchers diet, was measured for her wedding dress on Saturday and has dropped another dress size.
"I feel more determined than ever but I also don't want to let myself slip," she said.
"I know I need to stick to it because I've still got to lose one more inch off my waist to fit into my dress comfortably."
Lisa Jane now feels confident enough to stop buying Weightwatchers products and, instead, use a recipe book to make healthier meals which the whole family can eat.
She said: "I'll never ever go back to being the weight I was.
"I never want to feel that way again - looking at my wardrobe and thinking 'what am I going to wear today which doesn't make me look huge'.
Lisa Jane and her bridesmaid Lyndsay are trying out two different diets
"Now I can get up in the morning and pull on whatever I want, and I am loving the fact that I can go into shops and buy things rather than shopping online or in catalogues."
Lyndsay is still following the Cambridge diet which replaces meals with shakes, but this time she feels she can stick to it.
She wants to lose a total of 8st.
"In the past I've been in such a rush to lose the weight. I've gone to the meetings and maybe only lost half a pound in a week but got 8 or 9st to go, so it seemed impossible. I think that's why I've fallen off the wagon so many times.
"Now something's clicked that it's coming off and if it takes a year or two, that's fine."
"When I saw myself in your pictures it was shameful for me, I just couldn't believe I'd got to that point because I didn't see myself as looking like that. I can't wait to get the final fitting of my dress and feel amazing."
For this series I've been working with scientists Julian Mercer and Dr Alexandra Johnstone, from the University of Aberdeen's Rowett Institute, who have studied more than 50 types of diet.
JULIAN AND ALEXANDRA'S TIPS FOR SUCCESS
Weigh yourself regularly
Even small amounts of weight loss are very beneficial
Make changes you can stick to long term
Keep a food diary
Plan your meals
Find enjoyable exercise
Brain and hormone specialist Alan Mercer said: "Anyone who's concerned about their bodyweight should weigh themselves regularly, preferably every day.
"If you've put weight on, it's much easier to make small adjustments the next day rather than wait until your weight has run away with you."
"Also, be realistic about the level of bodyweight that you can expect to lose.
"Although people might want to go down two or three dress sizes, even quite small amounts of weight loss can be beneficial in terms of health and life span."
Nutritional scientist Dr Alexandra Johnstone said: "Start planning what you're going to eat and when, so you can count calories and know you're not going to be hungry. Enjoy food, enjoy life and enjoy exercise.
"Choose a form of exercise that you're going to keep up over a period of time and enjoy doing."
Dieters Lisa Jane and Lyndsay have their own words of advice.
'It's something you need to do for yourself," said Lisa Jane.
"Personally, I was kidding myself on. I was constantly starting diets, and by March I'd have fallen off them and put more weight on than I started with. But if I can do it - and I was the world's worst dieter - then anyone can do it".
Lyndsay said: "If anyone thinks they've got too much to lose, just give it a go - I believe there's a diet out there for everybody. It's the best feeling in the world. Go for it!"