Do you believe in strictly Calories In - Calories Out?

A couple questions. I used the search function but some of the info may be outdated - not sure.

#1) Do YOU believe in strictly calories in - calories out? As in, you could eat all of your calories in pure table sugar, and although its incredibly unhealthy, you would lose weight if you're in a caloric defecit? If so, is there ever a situation where a caloric deficit would NOT lead to weight loss?

If you define calories in as calories that are actually absorbed by the digestive system into the blood, then yes.

Maybe there are some medical exceptions, whereby calories in can't be used, e.g. type one diabetes - the lack of insulin means that the sugar can't get into the cells, the sugar ends up in the urine and the person's cells are starving. So yes, medical exceptions may be the case... but you can argue even in this case that the calories are not going into the cells, therefore they're not going in.

The guy who did the twinkie diet is the nearest experiment to what you suggested - it's not far from a diet of just pure sugar... yes if you ate at a deficit and nothing but sugar, you would lose weight. although the weight you lose will be lean body mass as well as fat, as your body will need to catabolise skeletal muscle to get the amino acids you need. Your health would suffer due to the lack of all the other nutrients the body needs and you'd probably die of kwashiorkor or some other protein deficiency disease before too long. (the twinkie diet guy supplemented his diet with protein powder and vitamin/mineral pills) But yes you would lose weight if you're in deficit... if you're eating a surplus of just pure sugar the excess would be stored as fat while the body would still have to catabolise your skeletal muscle to get amino acids, so you would end up extremely unhealthy, with too much fat and too little lean body mass.

I would never recommend a diet where the *only* thing you pay attention to is the calories - but calories in v calories out determines whether you lose weight or not... proper nutrition is for health and body composition. This is important to understand because so many people try hard to eat healthy and exercise, and then don't lose weight... because they're not in a calorie deficit. They wonder what they're doing wrong, and they are healthy and well nourished in all other aspects of health, but they're carrying too much fat that just won't go... it won't go because no matter how healthy their diet and how much they exercise, if they're not in calorie deficit, they won't lose weight.

#2) Ever since I introduced weight lifting (bench press, squat, dead lift, shoulders) 3 weeks ago, my weight loss has screeched to a snails pace (1 pound or less per week while being in a 2.5 pound caloric deficit). It is common knowledge that you don't build muscle while in a caloric defect. Am I holding onto water in the muscles for nearly 3 weeks now? As soon as I get my hands on a tape measure large enough I'll start measuring.

Your muscles are storing more glycogen. This is a good thing and it's part of what makes you fitter and stronger. That makes them retain water. Yes, this masks fat loss on the scale and can do so for a while before the weight starts going down again... but if you really are eating at a deficit you will be burning fat.... Just that the weight of the fat being burned is offset by the weight of the water and glycogen your muscles are storing. It's also possible that your bone density is increasing - again this is a very good thing. Denser bones are heavier (your bones stay the same size/volume as before) so this is something else that will offset scale weight. But during all of this, your body is still burning fat as long as you're in deficit. It may not be noticeable, because you may be losing fat from places, e.g. upper back, that people don't measure with a tape measure or observe in the mirror. Which is why it's a good idea to take progress pictures from different angles, not just focus on belly flab. But if you're really in a calorie deficit, you'll be burning fat.

Please, in this situation, you need to ignore the scale and focus on the mirror and the tape measure, and the fact that you're improving your health and fitness too. The scale will catch up if you have a significant amount of fat to lose. If you only have a little fat to lose, then the scale might never catch up but really, if you fit into clothes a dress size or two smaller and look fitter and leaner, then why worry about what the scale says?

ETA: if you're new to weight training and were overfat when you started, then it is possible that you have gained some muscle, aka noob gains. This also would offset scale weight, but this is a one time gain and will not offset scale weight indefinitely. And if you're female, it won't be that much. For a young (especially adolescent) male, it could be quite a bit (although adolescents shouldn't be eating at a deficit without a paediatrician's supervision)

#3) If Insulin stores fat, how do we lose weight while eating carbs and sugars (even in a caloric deficit) while insulin levels are elevated?

Biochemistry isn't my forte, but I'll have a go at this one. Insulin does not stop your body from burning fat. If you're in a calorie deficit, initially the shortfall will come from your body's glycogen but it will also start to use fat from your fat stores to make up the shortfall. The myth that you have to deplete all the sugar and glycogen from your body before fat burning starts comes from low carb gurus. It's not true. Your body balances fat and sugar burning, depending on what activity level you're doing at the time.... if you're pottering around at home you're probably running off mostly fat (but the total number of calories burned a minute is low)... if you're sprinting, you're running mostly off sugar, but you're still burning fat and the total number of calories burned a minute is much higher. More intense exercise requires more sugar, because your body can only burn so much fat at any one time. Insulin does not stop fat from being burned, nor does the presence of sugar in your blood. Your body runs off both, and insulin's role is in enabling the cells to use the sugar in the blood, and IIRC it has a role in fat storage, but it also has a role in the uptake of protein. Like I said, biochem is not my forte, but the picture painted of insulin being "bad" and "insulin is why carbs make you fat" is misleading. Carbs don't make you fat and insulin isn't bad. Anyone with type one diabetes can tell you just how important insulin is....

As to calories in/calories out: For weight loss, yes, For nutrition, no.

Alright you fit mother f#*+ers, educate me

Do you know flaming is against the terms of service here? You might want to think about that and cut it out since you only have two posts to your name.

For the record, OP, I thought that line was funny as hell :laugh:

1) No, but for all intent and purposes, Yes. While it isn't a perfect relationship and substrates may influence loss, the largest single influence is calorie deficit results in weight loss.
2) edema for exercise, glucagon replenishing from weight lifting, tom, changes in exercise that influence digestion rates, etc... can mask fat loss for weeks. Give it time. I personally take about 2-4 weeks after a significant program change to come back to a loss.
3) insulin induces cellular uptake of lipids and glucose and inhibits glucagon release, fat use, gluconeogenesis.... However, your body is using energy constantly so the storage uptake is counter balanced by the energy used. It's like if you said, how does the car run out of gas if the needle went up when we filled the tank. What happens looks like this....