Why Your Energy and Your Weight Are the Same Problem
- Jul 27
- 8 min read
Updated: 4 days ago
Darren Tebbenham is a metabolic and mental health expert known for the idea that metabolic health is mental health. A former university lecturer in exercise psychology, he co-founded Gloo Fitness, authored two books, has trained more than 3,000 health professionals from 30+ countries & now speaks to organisations on energy, wellbeing & performance.
It’s 3 p.m. You’ve had three coffees. You’ve even taken your magnesium and vitamin D, but you still feel tired. You are not lazy. You are not weak-willed. You have probably tried harder and more often than the people who have never had to think about any of this at all.
Yet, here you are. The weight is still there, too. I want to suggest something that might sound strange at first: You have not been failing at two separate problems. You have been circling one problem from the outside without ever being shown the thing in the middle.
The scale has been lying to you for years
Most people who want to lose weight have been trained to measure exactly one thing: a single number on a bathroom scale each morning.
That number tells you almost nothing useful. It cannot tell you whether you have lost fat or muscle. It cannot tell you how much fat is sitting around your organs, which is the kind that matters most for how you feel. It goes up when you drink plenty of water and down when you are dehydrated, and it has an unmatched ability to ruin an otherwise perfectly good day.
Here is why that matters more than it sounds. When people diet hard and repeatedly, they often lose muscle alongside fat. Muscle is metabolically active tissue. It is a meaningful part of the engine that burns your energy and helps manage your blood sugar. Lose enough of it across enough attempts, and each new attempt starts from a slightly worse position than the last.
So, the pattern many people describe to me is real. It genuinely does get harder. That is not a character flaw. It is a consequence of measuring the wrong thing and then optimising for it.
Something else worth noticing
There is another possibility that people rarely have pointed out to them, and it is this: Some of what you are feeling may be coming from the very things prescribed to help you.
A great many common medications list fatigue or weight gain among their effects. Some blood pressure medications. Some antidepressants. Steroids. Certain treatments in mental health care, which are well documented as affecting weight and metabolism. Hormonal treatments.
None of that means the medication is wrong or that you should stop taking it. Please do not change anything you have been prescribed without speaking to the person who prescribed it. But it does mean that if you have been quietly blaming your own discipline for the last three years, you may be carrying something that was never yours to carry.
Then there is the bigger observation, the one that changed how I look at all of this. Look at what tends to arrive together. Type 2 diabetes. Heart disease. Fatty liver. Polycystic ovary syndrome (PCOS). Erectile dysfunction. A harder-than-expected menopause. Depression and anxiety. A rising risk of dementia in later life.
We treat these as separate conditions, managed by separate specialists, in separate appointments, with separate medications. But an increasing body of research keeps circling the same underlying thread running beneath a surprising number of them.
The common thread behind your energy and weight
That thread is insulin resistance and its close relation, metabolic inflexibility. Insulin is the hormone that lets your cells take in energy from your blood. Insulin resistance is what happens when your cells stop listening properly. Your body compensates by producing more and more insulin to get the same job done, and for years, often a decade or more, this happens completely silently. Standard blood sugar tests can look perfectly normal throughout because the system is still just about coping. It is only when the compensation finally fails that anyone gives it a name.
Metabolic inflexibility is the practical consequence. A healthy metabolism switches easily between burning carbohydrates and burning fat, depending on what is available. An inflexible one gets stuck. It struggles to access your fat stores for fuel, which means you are dependent on your next meal to feel functional. It also means that the fat you are trying so hard to lose is remarkably difficult to persuade your body to give up.
Sit with that for a second because it explains an enormous amount: the 3 p.m. crash and why it arrives on schedule, and why you feel shaky and irritable if a meal is late while other people apparently just get on with their day.
It explains why cravings feel like a moral test you keep failing when, in fact, your body is asking for fuel it cannot reach in any other way. It also explains why the weight will not move, regardless of how disciplined you are, because you have been trying to burn fat with a system that has largely forgotten how.
Two different symptoms. The same root. That is why treating them as separate projects has never quite worked.
I should be honest about where the science is firm and where it is still being written. For type 2 diabetes, Polycystic ovary syndrome, fatty liver, cardiovascular disease, and erectile dysfunction, the link to insulin resistance is well established and not seriously disputed. For depression, dementia risk, and some other conditions, the associations are real and consistently observed. Researchers are still working out how much is cause, how much is consequence, and how much involves both feeding into each other.
Metabolic psychiatry, the study of how metabolic health shapes mental health, is one of the most interesting fields in medicine right now. Dr Georgie Ede, along with researchers at the Universities of Oxford and Edinburgh, is leading the way in this field.
But you do not need the science to be finished to notice the pattern. You certainly do not need to wait for it before finding out where you personally stand.
What this means for you
Here is what is almost never measured in any of this: your metabolic health. Metabolic health is how well your body produces, stores, and uses energy. It shows up in your blood sugar regulation, blood pressure, triglyceride levels, and how much fat sits around your organs rather than under your skin.
It is the closest thing we have to a direct read on that underlying system, and unlike almost everything else in this article, it is something you can find out about yourself.
There is one more piece worth knowing. The brain accounts for roughly 2 percent of your body weight and consumes about 20 to 25 percent of your energy. It is the most metabolically demanding organ you own. When your energy systems are struggling, your mood, focus, and patience are running on the same struggling supply. That is the bit almost nobody tells you: This was never only about your body.
Why the magnesium is not working
I have nothing against magnesium, vitamin D, electrolytes, or whichever supplement is currently circulating. Some of them have reasonable evidence behind them, and if a deficiency has been identified, correcting it can genuinely help.
But most people are not taking them to correct an identified deficiency. They are taking them because they are exhausted, and it is the one lever that felt available.
The same is true of caffeine. Caffeine does not create energy. It blocks the chemical signal that tells you that you are tired. The tiredness is still there, accruing quietly in the background. Because caffeine lingers in your system far longer than most people realise, the coffee that gets you through the afternoon is frequently the same coffee that degrades the sleep that would have fixed the tiredness in the first place.
Poor sleep then makes your body handle blood sugar less effectively the next day and shifts your appetite hormones toward wanting more. This produces more fatigue, more cravings, and another coffee.
None of this is a willpower problem. It is a loop, and you cannot willpower your way out of a loop. You have to interrupt it somewhere that actually matters.
Make it visible, then make it mean something
I have spent two decades in the gap between knowing and doing, first as a university lecturer and now coaching people directly. In that time, I have become certain of one thing: Information alone changes almost nobody.
What changes people is when something abstract becomes personal. Measure it. A two-minute body composition scan replaces that single misleading number with a real picture of your muscle, fat, visceral fat, and metabolic markers. Your numbers, with your name at the top. I have watched people go quiet while looking at that page. Nothing in an article does that, including this one.
Understand it. Data without meaning gets filed and forgotten. The value lies in connecting what the scan shows to what you actually experience, such as the 3 p.m. crash, poor sleep, and cravings that arrive on schedule. Once those stop feeling like personal failings and start looking like predictable outputs of a system, something shifts.
Change it. Then, and only then, does a plan make sense. It should be built on habit and identity rather than willpower and restriction, because willpower is famously unreliable, and restriction is what got most people into the cycle to begin with. The goal is not another aggressive six weeks. It is to build an engine that works while protecting your muscle.
The prize is not the number
Here is what I have seen happen when people finally address the middle of this rather than the edges. The fat loss happens, and it tends to hold, because it is a consequence of a system working rather than a temporary state maintained by heroic effort. The energy comes back, and honestly, most people notice that first, weeks before anything visible changes.
But the part people rarely anticipate is what happens in their heads. The fog lifts a little. Patience returns. The low, grinding background hum of feeling stuck, along with the sense that your own body is an unreliable thing you are fighting, starts to quieten.
Some of that is physiological, and the evidence linking metabolic health to mood is real, although it is more complicated than any single article can claim. But some of it is simpler than biology. There is a particular kind of exhaustion that comes from repeatedly trying and repeatedly failing at something you have been told should be straightforward. Discovering that it was never a moral failing, and that there was a measurable factor nobody had shown you, is its own kind of relief.
If you are tired, stuck, and out of ideas, please hear this clearly: You have not run out of willpower. You have been aiming at the wrong target, using the wrong instrument, for a long time. You cannot change what you cannot see, so go and look.
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Read more from Darren Tebbenham
Darren Tebbenham, Metabolic & Mental Health Expert
Darren Tebbenham is a leader in metabolic and mental health, behaviour change, and human performance. A former university lecturer in sport and exercise psychology, he grew frustrated that knowing what to do rarely helped people actually do it, so he left the lecture hall to build methods that change behaviour from the inside out. He has since dedicated his career to helping people and organisations transform their health, energy and performance, having trained over 3,000 professionals across 30+ countries and co-founded Gloo Fitness. His mission is simple: metabolic health is mental health. Body and mind are inextricably linked, and both perform at their best only when we treat them as one.
This article is for general information and is not a substitute for individual medical advice. If you are experiencing persistent fatigue, unexplained weight changes, or low mood, please speak to your GP.
