That's the problem - most likely they've tried hundreds of diets and couldn't stick to any of them.

Most of them were likely low fat/calories in-calories out diets:

Cut your intake to 1,000 calories/day.
Eat no more than 1,200 calories/day.
Count every single calorie.
Fiber calories don't count.
Eat at least 45 g of fiber daily.
Eat 3 meals a day.
Skip breakfast.
Cut out snacks.
Eat 6 small meals a day.
Sugar is fine, just stay away from all fats.
Eat only polyunsaturated oils.
Stick to plain chicken breast and broiled white fish.
Throw out your egg yolks.
Fill up on vegetables and fruits.
Eat lots of whole grains.
Switch to a vegan diet.
Switch to a vegetarian diet.
For sweeteners, use only honey and maple syrup.
Eating organic is the only way to lose weight.
Nothing is off limits - you can eat anything you want, just count the calories.
Limit everything, including vegetables and fruits, because every calorie counts.
Don't eat too much protein - you don't need more than 54 g/day.
Use meat as if it's a condiment - a little goes a long way.
Cut out desserts.
If you're going to eat dessert, make that your meal.
Eat these overpriced pre-packaged meals - delivered right to your door.
Follow this complicated point system that allows you to eat almost unlimited amounts of individual ingredients, but as soon as you combine them, they use up half your daily points.
Eat lots of fiber to feel full.
Exercise a minimum of 1 hour daily.
Isometric exercise is more important than aerobic exercise.
Aeorobic exercise uses more calories than isometric exercise.
One type of exercise is as good as another.
Weigh daily.
Don't weigh more than once a week.
If you don't see a drop on the scale every day, you're doing something wrong.
Drink a glass of water before each meal so you feel full faster.
Eat less.
Take these supplements to promote weight loss.
Our supplements work better for weight loss than their supplements.
You don't need to change anything - just take this pill and the weight will melt off overnight.
If you're not sweating, you're not exercising enough.
Use small plates so it looks like more food.
Think about every bite you take before putting it in your mouth.
Remind yourself that nothing tastes as good as being thin feels.
Buy goal clothes so you have a tangible goal to work towards.
When you lose a certain amount of weight, celebrate and have a treat.
You can have cake, cookies and donuts, just count the calories.
If this diet doesn't work, it's your own fault.

I'm sure there's more.


They've probably even tried an assortment of low carb diets, and failed to stick to those too.

Here's a list of low carb diets referred to on this site alone:

http://www.lowcarb.ca/atkins-diet-and-low-carb-plans/

Not exactly a short list, and each LC diet has it's own little differences.

I fully admit that it is not at all easy to stick to LC, especially at first when you're going through induction flu. And it can be difficult even after that because LC requires eating almost the exact opposite of what most everyone else eats, and definitely still not what dieticians recommend, or what most people would think of as a diet.

Over the last 50+ years, I was on and off (mostly off) LC at least 3 times.

There's unfortunately some crazy cult LC diets too (Kimkins - thankfully, I felt so awful on that after only a few hours that I decided it was definitely NOT for me). There's always some new diet craze out there.

The semaglutide drugs are just the latest.

And I think for some people they've tried so many diets so many times and failed at all of them, so these drugs are their only hope of losing weight because they've tried everything else and simply couldn't stick to it.