My friend’s son reminds me how important blood sugar control is to energy and mood

I was talking to a son of a friend of mine over the weekend. Mark (not his real name) is 18 and has been finding his energy and motivation can flag at times. Some of the time he can be energised and motivated. Other times he feels lethargic and “can’t be bothered with life”. Naturally, the focus on this issue has been on his life circumstances, but I was also interested to explore if physiological or biochemical factors may be playing some part in his symptoms.

I asked Mark if his symptoms appeared to have any relationship to food. He said others had noticed that his mood improves, at least momentarily on eating. There are many reasons why someone may feel cheerier for eating including, of course, the deriving of pleasure from food. One other important reason individuals may feel better for eating is that they have come into that meal with low levels of blood sugar (hypoglycaemia).

Because the brain generally uses a lot of sugar, under-fuelling of the brain through hypoglycaemia can cause it to malfunction. Low mental energy and low mood are potential symptoms of hypoglycaemia. When blood sugar levels are improved by eating, it can lead to an improvement in energy and outlook too.

I have found over the years that blood sugar instability is a major cause of fluctuation in mood and energy. This has not just been my professional experience, but my personal experience too. Many years ago (when my diet was much richer in carbohydrate) I was quite prone to what I take to be spells of hypoglycaemia myself.

While I talking to Mark I remembered how I would sit as medical student in teaching hospital clinics or lectures in the afternoon (a danger time for hypoglycaemia) feeling tired, unable to concentrate and often utterly demotivated. Later on I began to realise that at least a large part of these issues were down to my awry blood sugar control. This was picked up on by others too. For example, if I was grumpy those who knew me well (a girlfriend, say) would urge me to ‘eat something’. One of my friends, a doctor, suggested that I was Snow White’s eighth dwarf – going under the name of ‘hypo’.

I have learned, likes many others, that getting the diet right is key to stabilising blood sugar levels. There are two fundamental here: eating foods that release sugar relatively slowly into the bloodstream, and eating those foods regularly enough.

I asked Mark about his diet. A lot of his diet turned out to be generally disruptive for blood sugar (Subway sandwiches, burgers and fries, mounds of pasta). His eating was also quite irregular. I asked about breakfast. His reply was “I don’t see the point of breakfast”. I asked him what he meant by this and he replied “When I eat breakfast I’m starving an hour later.” When I asked him what he might have for breakfast it turned out to be cereal.

His experience here is relatively common. I quite often hear individuals tell me they are hungrier in the morning after the eat breakfast than if they don’t. This, I think, is another symptom of impaired blood sugar regulation. Typical breakfast fare such as toast and cereal tend to induce surges of blood sugar which, in turn, can cause large quantities of insulin to be secreted by the pancreas. One of the chief functions of insulin is to reduce blood sugar levels, but a glut of insulin can cause hypoglycaemia, which can cause individuals to be hungry (typically for carbohydrate-rich foods).

My advice was to scale back the carbs a bit, up the protein, and to eat more regularly (including healthy snacks if he gets peckish between meals). Cutting back on carbs and eating more regularly should help to ensure a steadier supply of fuel into the brain. More protein should help here too. But another trick that protein has up its sleeve is the fact that it is made of amino acids, and these supply the building blocks of brain chemicals (neurotransmitters) that can have a profound effect on mood and brain energy (including dopamine, noradrenaline and serotonin).

Giving advice is no guarantee that someone will act on it. However, my experience tells me that if Mark adjusts his diet in the way I outline here he will see quite immediate benefit in terms of his energy and mood. I know it did with me, and I’ve seen it work for countless others too.

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22 Responses to My friend’s son reminds me how important blood sugar control is to energy and mood

  1. Gary 8 February 2010 at 1:18 pm #

    I work as a specialist dietitian dealing with diabetes in the NHS. Anybody who regularly experiences hypoglycaemia is likely to have adrenal insufficiancy. A hallmark of which is low cortisol. Cortisol is very important for buffering the blood glucose at all times of the day. But it is particlarly noticable around 3pm when cortisol is usually at its lowest. A saliva DHEA test can check this.
    Most people don’t feel like eating first thing in the morning as cortisol levels are highest at that time of day. Often due to the stess hormones the liver is chucking a out extra glucose.
    We see this in our Type 1 Diabeteic who don’t eat breakfast. Their blood glucose often increases in the morning despite no food.

  2. Dr John Briffa 8 February 2010 at 1:50 pm #


    I agree with you regarding the link between hypoglycaemia and adrenal fatigue/weakness. I think it’s important to make the point that some individuals do not have adrenal insufficiency (Addison’s disease) but nonetheless have compromised adrenal function.

    I also agree that salivary testing can be useful for checking for this. However, is there a reason why you only check DHEA levels? When I run this test, I routinely check for cortisol too. Is there any reason why you do not do this?

  3. Nigeepoo 8 February 2010 at 2:24 pm #

    I wonder what percentage of the population has an impaired Phase 1 insulin response. This messes up the step response of the blood glucose regulation negative feedback system (speaking as an ex-Electronic Engineer!), causing overshoots & rebounds.

    For those who have no idea what I’m talking about, see Blood Glucose, Insulin & Diabetes.

  4. Gary 8 February 2010 at 2:34 pm #

    Dr Briffa,
    I would say that many people have adrenal weakness due to the stresses of modern life etc. This isn’t to be confused with Addison’s Disease which is much more serious and life treatening.

    Testing cortisol certainly is useful alongside DHEA. Often patients with adrenal fatigue are prone to mineral imbalances as the adrenals become weaker. For example they often become copper toxic as the adrenals can’t produce enough ceroplasmin to make copper available for metabolism and the copper ends up getting dumped in the brain kidneys or liver. Unfortunately these mineral imbalances are hard to detect.

  5. Chris 8 February 2010 at 5:11 pm #

    John and Gary,

    Mark has the kind of polarised outlook on life that afflicted me at that age. How much might male sex hormones be disruptive?

    His diet does sound poor, but not atypical to the diet of many of those of his age. The description suggests high in refined carbohydrate, high GL (glycaemic load), high refined cereal content, low in soluble fibre, low nutrient diversity, and high in vegetable oils. These are the striking dietary deviations of the industrial age. Is Marks’ diet also high in sucrose?

    A consequence of the onslaught of this irregular high aggregate GL diet would be a very ‘peaky’ insulin response and high mean levels of insulin, wouldn’t it, which could be the cause of his hypoglycaemia and therefore of the lethargy and moodiness?

    I have just seen TV footage of paramedics attending an elderly diabetic who was comatose and unresponsive. A blood test revealed low blood sugar. This diabetic was hypo and the paramedics administered glucagon intravenously.
    Sears describes glucagon as the axis companion to insulin helping to moderate insulin secretion and effect. Worthy of note is that glucagon is the bodies regulatory (autocrine?) response to digesting protein and in being so it helps to moderate insulin. So the advice to cut back on the carbs and up the protein would align with that.

    The diet of our ancient ancestors was never so high in GL as ours is now, but ancient and successive innovation in the evolution of the human diet incrementally made the caloric content of human food sources that little bit more readily available, in effect incrementally raising the GL of the diet. This is a thought and interest originating from reading ‘The True You Diet’.

    The mention of the adrenal response intrigues me. How disruptive is adrenaline to insulin and/or blood sugar? I bring personal experience to this too. As a driver I have noted that the combination of congestion, destination, deadlines and a ticking clock can raise my stress levels and raise BG meter readings. Stress can be a factor, yes? I now avoid those features in my choice of work.

    Being aged 50 and type 2 diabetic I think a lot rides on Marks’ dietary habits and lifestyle choices as it does for many of his age. For me the awareness has come a little late in life and at age 18, even had somebody gone to lengths to explain it to me, I think I would have had difficulty grasping the implications. Sweet, fast and convenient would have appealed over the long view.

    I would extend my very best of wishes to Mark.

  6. Jake 8 February 2010 at 6:01 pm #

    Since I switched to zero carbs for lunch and breakfast, I have no swings in energy during the day.

  7. Gary 8 February 2010 at 9:43 pm #

    Low carb diets for Type 1 & Type 2.

    Anybody with Type 1 Diabetes contemplating this sort of diet would need very close supervision.

    As for Type 2’s, no problem as long as they aren’t on sulphonylureas or similar oral hypoglycaemic agents.

    I believe the diet can be of little risk to health and indeed beneficial especially in cases where patients have severe insulin ressistance. obesity and other co-morbidities. The problem for alot of patients is that they get bored with high protein low carb diets and can rarely maintain them.

  8. Nigeepoo 9 February 2010 at 1:08 am #

    Gary, would you like to comment on low-carb diets for people with T1&2DM as proposed by Bernstein, Christie, Shwarzbein, Ruhl etc?


  9. Nigeepoo 10 February 2010 at 4:41 pm #


    It’s weird you being in a different time zone from me. Your reply appears before my question.

    RE: “very close supervision”. Would regular (morning, pre & post-prandial) self-monitoring of BG be close enough? Lower-carb diet obviously means lower-dose bolus insulin. Basal dose should be much the same.

    People need to learn how to cook. There are so many low-carb foods out there other than bacon & eggs. Dr. A’s SITE and BLOG has a veritable cornucopia of recipes.

  10. Di 12 February 2010 at 11:56 am #

    Can you recommend to me, a layman, specific foods containing protein, for breakfast – I normally have fruit. I’m not keen on meat, dairy or gluten – they seem to make me flatulent and bloat my stomach.

  11. Florence 12 February 2010 at 2:30 pm #

    Di, a couple of eggs – boiled, fried or scrambled – with your fruit would be great. Also, what about a bit of fish? Or just some nuts with your fruit?

  12. Dr John Briffa 12 February 2010 at 2:38 pm #

    Di and Florence

    a couple of eggs – boiled, fried or scrambled – with your fruit would be great. Also, what about a bit of fish? Or just some nuts with your fruit?

    I second that! (and don’t forget poached eggs too)

  13. Greg 12 February 2010 at 5:59 pm #

    I am type 2 diabetic and the post prandial readings encouraged me onto a low carb approach. I avoid processed carbs, cooked tarchey carbs, sweets and the like. Still drink red wine!

    Low carbs are not the answer for everything. They have worked brilliantly in me with PP around 5.5. Importantly I then trend towards 4.2 – 4.4 through the afternoon and then raise to 4.8 or so by 7pm. Surely this shows that people whose liver glucose function is fine do not get hypo. So there should be some other issues around the “topping up” glucose mechanisms, at least as well as.

  14. Katrina 12 February 2010 at 8:53 pm #

    Thanks for the blog post John, very interesting.

    Gary, I am type 1 diabetic and for 7 years have followed a low carb diet, my insulin requirement has dropped significantly and my average blood sugar readings are always excellent. I do agree though it has to be done under strict supervision, in my case with the help of an excellent nutrition consultant, who kept an intitial tight check on my blood sugar readings when embarking on the low carb plan and continues do do so. Sadly my hospital dietician’s advice left me taking large amounts of insulin which I felt awful as a result no eneergy at all. The low carb diet has worked the ppposite to this for me.

  15. Joanna 13 February 2010 at 5:34 pm #


    Your comments are spot on! Last year I was having the most horrendous hourly sugar crashes coupled with otherssymptoms including extreme tiredness.

    Long story short, was referred to an endocrinologist on the NHS and he didn’t have a clue! Just told me to eat frequently.

    A few months later had an Adrenal Stress Test done and bingo! my cortisol levels were way low. So this explained all the symptoms including hypoglycaemia.

    I wish endocrinologists were trained to diagnose and recognise adrenal fatigue as a real and debilitating condition.

  16. Gary 15 February 2010 at 4:43 pm #

    Unfortunately many doctors don’t believe that adrenal fatigue (not to be confused with Addisons Diasease) exists. An endocrinologist will mainly run short synacthen test with cortisol for adrenal function. I am not convinced of the accuracy certainly of the short synacthen test and therefore many patients remain undiagnosed.

    This is a very sad state of affairs. I believe adrenal fatigue is actually quiet common in the stressful world we live in and can leave a patient in a very poor state of health without any explanation.

  17. Katy 19 February 2010 at 6:24 pm #

    I am not diabetic but experience the exhaustion and low mood, relieved temporarily by eating, that you describe as symptoms of hypoglycaemia. These symptoms are relieved completely by taking Sucroguard, a formulation of B vits, magnesium and chromium that I think you initially devised for Biocare. Is this safe to take indefinitely?

  18. Amy 31 March 2010 at 8:41 pm #

    Please can you tell me a bit more about Sucroguard ” how effective is it and when did you start to see some relief? Im not a diabetic..

  19. diane woods 28 April 2010 at 7:12 pm #

    Does this sound like hypoglycemia to anyone?My daughter is 16,she checks her blood daily. It can be as low as 2.8, then within the hour it can be 4.2.The highest it has been is 6.2.But that was a one off. She feels like she has no energy a lot of the time.She always has cold hands,feels dizzy sometimes.Why is her blood readings so up and down all the time? I would be gratefull for any advice. diane


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