Does your weight effect your basal rates?

as a swimmer, i am physically fit. however in the last year, with no major changes in my diet, i have gained about 5 pounds (not bad ). but the thing that seemed to present itself right away with the weight change, was that i was needing to increase my basal rates across the board. and i went from a TDD of 17-18 units to a TDD of 23-28 units.

this really caught me off guard. however, i am certain at least one of you has an explaination or identification with this. am i crazy for thinking this???


@daisymae. You are not alone. My basal rates fluctuate with my weight as well. 1kg in either direction is enough to necessitate a profile change in my pump settings.


I think this is not totally surprising. Our endo calculates rough TDD based on weight. Whenever Samson’s TDD goes up, sure enough at the endo he’s gained weight.

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Basal metabolic rate (BMR) is the number of calories your body needs for it’s most basic life-sustaining functions.

For humans, BMR varies by size, age, activity level, and gender.

For illustration, let’s compare a 100 pound adult woman to a 15,000 pound elephant…

For a relatively active adult woman :swimming_woman: who weighs 100 pounds, she would need about 1,500 calories per day to maintain her weight.

Adult male African elephants :elephant: at the San Diego zoo eat over 70,000 calories each day (according to the San Diego Zoo).

It is not a perfectly valid comparison, because different animals have different metabolisms, but you get the idea. The more you weigh, the more calories you need. And the more calories you need, the more basal insulin you need…


Yes it varies by weight. I’m thinking now about how it should also vary by muscle/fat percentage; however, that seems complex to tease apart. On the one hand, if two people are the same weight but one has more muscle mass, that person needs more calories, since muscle burns more than fat. You’d think therefore, that higher metabolic rate would mean more basal insulin. However, more fat can mean more insulin resistance. Of course, muscle/fat percentage is likely explained primarily by a combination of sex hormones (testosterone promotes muscle building etc) and activity level (use it or lose it), both of which also influence insulin needs, potentially in the opposite direction from muscle requiring more calories and thus more insulin (especially activity levels). Hmm.


ok. i get this. but lets say that you cut out the calories a bit. would that mean that you need less basal insulin? and what’s the big deal with very low carbs on a keto diet? i know that insulin is linked to weight, and you need insulin to process carbs, but what if, for example, youre one of us Ds who needs to bolus for things like protein and fat? (nuts, fish, meat, etc) does that insulin “count” the same way as bolusing for carbs does? you are still giving your body insulin; does your body know the difference?

am i making any sense whatsoever? i really hope so.

Yes. A reduction in calories leads to less basal requirements, less overall insulin needs, and eventually less weight.

There are a lot of other factors, like a person’s metabolism and diet choices, but the simplest formula for weight loss is that you are burning more calories than you are consuming.

So in simplest terms, they all go directly hand-in-hand - a reduction in calories, less insulin requirements, and weigh loss.

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OK, so here goes my next question: before i was swimming, i had a hard time digesting carbs like flour (bread, basically) i just focussed on protein and fat (peanut butter, cheeses, olive oil, mayo, ) all high calorie foods. i was easily consuming 2,500 cal/day and, at the time, i weighed 100lbs. since i’ve been swimming, i have needed those carbs to keep afloat and not crashing post swims. they work. no doubt about it. and my body seems to have adjusted well to incorperating the carbs. However, since i began including the carbs and reducing (or even elimenating ) the fat, my total daily cal intake has gone down to 1,500. that 1,000 cal LESS per day. and, when you include the exercise, i should have a rather large caloric deficit. so why have i gained weight?

makes no sense to me at all. is there a reason for this? the only thing i can think of is that i am using less insulin when i am not eating carbs and rather focusing on fat and protein.

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We’d need to really look closely at your caloric intake before and know how much you were eating before versus now. And also what your BMI was then versus now.

BMI is Body Mass Index, and it is a measure of your body fat (compared to muscle).

If you are more muscular now, you might have gained weigh from adding muscle in place of fat.

Muscle tissue is more dense than fat tissue. So even if your pants size goes down, you can still add weight!

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this is all good to know, bc i have definately put on muscle since swimming. however, since its a very hot summer, i have been living in my shorts and havent tried to fit into my blue jeans since the spring time. :wink:

For what it’s worth, BMI is a terrible measure on an individual level generally (it is designed really for population level research, but it kinda sucks at that too). It does not differentiate between muscle and fat, which is why very muscular people are frequently categorized as obese even when they are in excellent shape and have low amounts of body fat.

The only thing BMI is useful for is things where mass regardless of muscle or fat is important. For example, risk of cognitive impairment with aging is apparently linked to body mass, whether that mass is muscle or fat.


this is all so technical and confusing, and a question i would like to reiterate is why can i maintain a thinner weight by eating more calories while doing less physical activity. why do carbs have such a great impact on weight? is it that they need more insulin to consume the carbs and thus, bc insulin is a hormone , we are responding to the increase in insulin levels?

however, the only way that this could work would be is if i did not have to take insulin for fat and/or protein; but, and again YDMV, if i am having to take insulin for things like fat and protein, i am still utilizing insulin, therefore, i should weigh the same as on a carb friendly diet.

More activity (in general) also changes your metabolism. So you might burn more in general than when you were not active.

But I am not sure why you are saying less physical activity. What time-frame are you looking at?

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By thinner weight, do you mean just lower weight? Because it’s better to judge by how your clothes fit than weight, because muscle is denser (weighs more) than fat. So if you work out, your weight may actually increase as you replace fat with muscle and/or just build additional muscle. You may either get smaller or stay the same size (but have more definition). That’s all typical, especially if you aren’t carrying much extra body fat to begin with, which I believe you were not, right?


before i began my swimming, the only physical activity i was doing was walking daily. i may have been walking between 1/2 hour to 1 hour a day. thats it. no other physical activity than that. i ate pretty much everything i wanted, which included lots of fat (tubs of peanut butter, layers of butter on everything, nuts,high fat cheeses,) and lots of protein. (fish, chicken, turkey, eggs ).

in between writing this and reading the responces, i have tried on my go-to favorite jeans. they are way too tight, clearly this is not just bc of muscle density related weight.

PS: i dont mean to imply that i am in any way “fat” bc i am not. i just weigh more and i am larger in size than i was since i switched from a high protein, high fat, low carb diet, to a diet with more moderate amount of carbs every day and protein rich foods with very little fat.

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Gaining weight now—in the name of science. I look forward to chiming in on this in another couple of pounds.



do you mean that you are busy eating? i hope its yummy. :wink:

I do think that insulin is a fat storage hormone. IF eating more carbs requires more insulin, you are likelier to hold on to the weight. However, people also put on an average of a pound every year. How long has it been since you’ve consistently eaten a low-carb diet? If it’s been a few years, it might also just be normal that you weigh more than you did, say, 5 years ago.


i cut out all bread for the past 1+ week bc i was having some digestive problems and thought it might be wheat related(gluten problem)

still havent figured out what the problem is (i see my GI specialist this coming wednesday) but i did shead a pound!