A year ago Amy Clarke struggled to run up the stairs, but this week the geologist from Hundleby is climbing to the slope of Mount Everest.
Amy, 28, is due to arrive at the mountain’s 17,500ft high base camp next week.
She has embarked on the three-week expedition to help survivors of the devastating earthquake that struck Nepal in April.
On the ascent she will be enduring night-time temperatures of minus 15 and the oxygen sapping altitude.
Amy has been able to embark on the challenge after shedding more than four stone in the last year.
The transformation started after she joined the Slimming World group in Spilsby where she was able to draw on the support and encouragement of fellow members.
Amy said: “I needed someone to push me as it would be very easy to not stick to the diet when no-one is looking.
“There is no way I could have climbed Everest if I had not lost the weight and doing gym work has allowed me to get it off a little bit faster. I used to find it quite hard just running up the stairs, so there has been a massive change.
“I don’t think I used to eat particularly unhealthily, it was just that the portion sizes were a bit much.”
A structural geologist working for Hundleby based Badley Geoscience, Amy will be undertaking the 16-day trek with cousin Katie Billingham. She is aiming to raise £2,000 for the Community Action Nepal charity.
It is expected to take 11 or 12 days to climb to base camp and three to four days to make the descent.
Amy was recently voted winner of the Miss Slinky award by members of the Spilsby Slimming World group for the inspiring example she has set others.
Group consultant Michael Burgin said: “I could not be more proud of Amy and what she has achieved. For me the main thing is she has grown in confidence and made new friends.
“It is amazing that she is climbing to the base camp to support the disaster fund. She would never have been able to do it without losing the weight, it would have been like carrying a big bag of potatoes.”
Anyone wishing to sponsor Amy should visit www.justgiving.com/AmyLClarke/