If 3500kcal deficit = 1lb weight loss, why doesn't it work?

[Watchkeys]

I'm just curious to know what people think about this. Lots of people on here are sticking to a deficit. It might not be 500kcal per day, but some increment of that would incur some increment of weight loss, if the theory holds. Millions of people are on kcal controlled diets, and mostly, they don't work, especially not long term.

What's going on?

human bodies are not the same as a furnace burning energy, that’s basically what calories are based upon.

Not all calories are equal when digested, they don’t react in the same way on their journey inside the body. High fibre food will behave differently from chocolate when consumed

not all calory labels are accurate

@BounceyB

If you go to the British Nutrition Foundation website there's loads of sensible advice which doesn't involve bullshit. The general advice on there has always been consistent with legitimate scientific theory

They are funded by food companies, and their facts and figures have often been queried for scientific validity.

I think the basic science is correct but it's a really individual thing. I didn't lose any weight eating 1000 calories a day, low fat -but just very small portions- late breakfast plus evening meal,

Nor did I lose weight at 1500 calories - normal food ,all accurately measured

But at 1250 calories of low carb, wholegarain only, good food , I lost 2 stone

I am not really sure what we are arguing about here but anyway....
A kcal cannot be worth different amounts of energy. A kcal is the amount of energy needed to raise 1kg water by 1 degree. (At around 15 deg). That doesn't change.
What changes is how a body uses those units of energy. And how accurately the kcal in food are calculated.
So for instance when my DD was recovering from AN it was true that 500 excess cal a day led to 500g of weight gain a week. But those kcal in her case went on organ repair. And then organ fat stores. Then starting her hormones back up. And then brain repair. Then she'd havr got 'fat' if she'd have carried on on that excess.
When she lost the weight (at a much faster rate as she put herself in a c 1000 kcal a day deficit) she first lost all her body fat, then her brain shrank, then her organs lost their protective layer of fat and then her heart started to give out.
So it is about kcal deficit. In my experience.
As an overweight species main lining UP shit we are just pretty crap at doing it.

I can tell you from my DDs experience cal deficit works. Period

One of insulin's primary roles is to encourage the body to burn sugar and store fat. That's a hormone.

So, it doesn't work, then? Or, you're saying, scientifically, it would work, but we can't replicate it in real life?
It relies on habit changes so that the healthier choices become automatic.

For example DH is openly more conscious about portion size than me. That's because he knows he's prone to eating what is served out, whereas I'll eat the same amount regardless of how much is served out. I manage my portions but don't have to calorie count and monitor everything and it wouldn't be sustainable long term to do that.

It's as much about long term behaviour change and habits as it is about eating X number of calories a day because some diet plan said so.

This is the explanation. A kcal is a kcal, but your body will use that energy as and how it needs to depending on your overall health. One pound of fat is equal to 3,500 kcal, but that doesn't mean a 3,500 kcal deficit will always mean one pound of fat loss.

Either this is a joke, or OP is trying to feign a lack of understanding from credible sources as an excuse to not lose weight.

When I said burnt I meant burnt to ash not burnt as fuel by a human who has eaten it.

“Food calorimetry allows us to determine the number of calories per gram of food. In this activity, a piece of food is burned and the released energy is used to heat a known quantity of water. The temperature change (∆T) of the water is then used to determine the amount of energy in the food.”https://www.carolina.com/teacher-resources/Interactive/food-calorimetry+/tr23949.tr#:~:text=Food%20calorimetry%20allows%20us%20to,of%20energy%20in%20the%20food.

Wrong on both counts. I know what I think. I'm not overweight.

I'm a Personal Trainer trying to get my head round why people think that the credible sources are credible.

Which credible sources are you referring to, and why do you believe them to be credible? Where do they get their information from, for example?

yes insulin is a major player but so is ghrelin and leptin.
and estrogen levels tend to affect the ghrelin and leptin more than insulin.
it also controls where are body fat is deposited, the abdominal fat becomes more problematic.

@WhatWouldJeevesDo

When I said burnt I meant burnt to ash not burnt as fuel by a human who has eaten it

Is this relevant, except to point out that this is what humans don't do, which challenges the same point I'm challenging in my OP? It seems we agree!

Glad to see there's a few here at least who seem willing to challenge what we're fed (literally)

@Watchkeys i follow dr. mary claire haver.
not all of what she says but as both a woman and gynecologist her understanding of the female body and hormones is excellent.
very much into low processed natural foods and more of it vs less. so avocado and nuts and legumes...veggies. meats that are lean with limited or no hormone additives.

When I said burnt I meant burnt to ash not burnt as fuel by a human who has eaten it.

“Food calorimetry allows us to determine the number of calories per gram of food. In this activity, a piece of food is burned and the released energy is used to heat a known quantity of water. The temperature change (∆T) of the water is then used to determine the amount of energy in the food.”

Yes, exactly. So, controlling this stuff is much more complicated than 3500kcal deficit = 1lb weight loss.

That's what I think but many seem married to the idea, despite the fact that they are overweight and desperate not to be.

Thanks @greenspaces4peace I'll look her up.

Sorry, was having connection problems. Posted twice.

Hadn't noticed, it's a fast thread!

Haven't read the whole thread, but I am 100% convinced that some bodies immediately adapt to a lower calorie intake. So instead of using up reserved fat for energy, they just slow down and adapt to the lower calories ingested. I know this from 45+ years of trying to manage my weight and generally eating quite modestly. I've never been a person with a big appetite or a binge eater.

@Watchkeys often the claim to be desperate is a desire to be a certain weight a number on a scale.
and most of these people want it to happen fast it's a really slow process unfortunately and very difficult to sustain.
especially if it's combined with both changes in food choices and exercise.
and for some people it's impossible if finances and employment don't permit it.
for example: shift workers, weight gain and night shift.

Because if you burn more than you eat, your body will start using reserves to keep you going.

but most people burn far less than they think. And many consume more than they think.

the idea that woman need 2000 cals is really pervasive yet is far more than most woman need (unless they do a lot of exercise).

@LindorDoubleChoc

I am 100% convinced that some bodies immediately adapt to a lower calorie intake

Yes, and I think it's a sign of good health, as long as too much weight doesn't accumulate. We're meant to be adaptable, and body fat is the energy storage system that's stopped us from dying out various times during our evolution. Being a person who can keep it is like being someone who can keep money in their savings account (although keeping it and having a rubbish diet is like keeping your savings and your debt)

Don’t be daft. Yes it does. Eating Keto is a method of creating a calorie deficit as the only way to lose weight is by creating one. Keto is a method. Protein has high satiety and a high thermic effect.

A deficit doesn’t have to be large or 500 calories for someone to lose fat. And it doesn’t have to be low calorie.

It depends what they weigh in the first place. A male weighing 20 stone would be in a deficit at 3,500 calories which is still loads of food. A kcal is just a unit of measurement.