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Very low calorie diets (VLCDs) FAQ

As I've had questions and sought out answers, I've logged them here. Hopefully this page can answer some of your questions in turn!

For additional resources, refer to Resources | Very low calorie diets.

What is the aim of very low calorie diets?

The diet aims to send type 2 diabetes into remission. Remission, for these purposes, is defined as maintaining fasting blood glucose of 7mmo/l or lower, without any medication.

Note

It is debatable whether "remission" or "reversal" is more accurate. I have opted to use remission: it conveys the sense that the disease has gone away, but can return.

What does a very low calorie diet involve?

Three stages:

  1. Up to 12 weeks on a VLCD, using meal replacement shakes.
  2. A transition period back to normal eating, reintroducing solid meals.
  3. Fairly normal eating, but probably at a lower calorie amount than you were consuming before, ensuring you don't regain weight.

Professor Taylor has published two books describing how the diet works:

  • Life Without Diabetes: The definitive guide to understanding and reversing your type 2 diabetes
  • Your Simple Guide to Reversing Type 2 Diabetes: The 3-step plan to transform your health

Newcastle University also provides a free PDF outlining the diet.

The NHS has a web page describing the program.

How fast can I see results on a very low calorie diet?

You may begin to see normal fasting glucose in as little as seven days, thanks to rapid improvement in the liver:

"In the first 7 days, fasting plasma glucose fell from 9.2 mmol/l to normal ... Liver fat fell by 30% during the first 7 days of negative energy balance." (source - pg4-5).

Pancreas functionality (driven by beta cell recovery) improved more slowly:

"Week by week during the Counterpoint study, the insulin response increased so that, after 8 weeks of diet, the first-phase response was within the normal range and the maximal insulin secretion rate was numerically but not significantly greater than that of the control subjects. The beta-cells had woken up!" (source - pg5).

First-phase response refers to the first phase insulin response. Insulin is released in two phases when you eat, and a reduction in the first phase is associated with starting down the path to diabetes: "The first phase consists of a brief spike lasting ~10 min followed by the second phase, which reaches a plateau at 2-3 h. It is widely thought that diminution of first-phase insulin release is the earliest detectable defect of beta-cell function in individuals destined to develop type 2 diabetes" (source).

Should I take diabetes medication while on a very low calorie diet?

Discuss medication changes with your doctor. This advice leaflet to doctors suggests medication may be reduced or stopped. If you're doing the diet without medical consultation (don't!), then be careful messing with your own meds.

What if I already have retinopathy?

If you are already experiencing retinopathy, the diet may not be safe: "the sudden normalisation (reduction) in retinal blood flow associated with the return of normal blood glucose control can disadvantage areas of the retina in areas of marginal circulation with resulting deterioration." (source - pg2).

Is this just another scam diet?

It's always sensible to be sceptical. I have slightly more confidence in this diet than usual, because:

  • It's available on prescription on the NHS.
  • It's backed by academic research at a good university. More information is available on the university website.
  • Professor Taylor doesn't seem to be making money off his work (he's not selling his own line of shakes, and he's donating the profit from his books to Diabetes UK (source).
  • No-one else involved in the research seems to be profit-making either: neither Newcastle University, nor Diabetes UK (the charity that helped fund the research) are selling products off the back of it.

What is the theory behind very low calorie diets?

The diet draws on the twin-cycle hypothesis. This is a theory that type 2 diabetes is caused by a build-up of fat around the liver, which reduces the liver's insulin sensitivity, and eventually leads to fat around the pancreas as well, which reduces its ability to produce insulin. These slides contain more info (quite technical), including some scans showing organ fat content. Worth checking out, even if the early slides aren't very comprehensible to those of us without a science background!

This means that if you lose the fat around your liver and organs, you remove the cause of type 2 diabetes. If your pancreas hasn't taken too much damage, it can recover (though perhaps not fully).

This lecture by Professor Taylor provides a helpful summary:

It has become widely accepted that Type 2 diabetes is inevitably life-long, with irreversible and progressive beta cell damage. However, the restoration of normal glucose metabolism within days after bariatric surgery in the majority of people with Type 2 diabetes disproves this concept. There is now no doubt that this reversal of diabetes depends upon the sudden and profound decrease in food intake, and does not relate to any direct surgical effect. The Counterpoint study demonstrated that normal glucose levels and normal beta cell function could be restored by a very low calorie diet alone. Novel magnetic resonance methods were applied to measure intra-organ fat. The results showed two different time courses: a) resolution of hepatic insulin sensitivity within days along with a rapid fall in liver fat and normalisation of fasting glucose levels; and b) return of normal beta cell insulin secretion over weeks in step with a fall in pancreas fat.

Now that it has been possible to observe the pathophysiological events during reversal of Type 2 diabetes, the reverse time course of events which determine the onset of the condition can be identified. The twin cycle hypothesis postulates that chronic calorie excess leads to accumulation of liver fat with eventual spill over into the pancreas. These selfreinforcing cycles between liver and pancreas eventually cause metabolic inhibition of insulin secretion after meals and onset of hyperglycaemia. It is now clear that Type 2 diabetes is a reversible condition of intra-organ fat excess to which some people are more susceptible than others.

What is a PFT (personal fat threshold)?

When we gain fat, it is stored under our skin. At a certain point, the body stops doing this, and instead stores it around our organs, including our liver. The PFT is a person's unique point where their body starts doing this.

I'm a healthy BMI, how can fat be causing my diabetes?

You can be a healthy BMI, but still exceed your personal fat threshold. However, dramatic weight loss is obviously risky if you're not carrying much weight. However, if you have exceeded your PFT, you will have a fatty liver. So losing that fat can still help.

Is remission guaranteed?

No.

The DiRECT trial published a two-year analysis (a report on results two years after the study). This report states that "At 1 year, 68 (46%) of 149 intervention participants were in remission and 36 (24%) had achieved at least 15 kg weight loss" (source - pg4). So slightly less than half achieved ongoing remission.

Will my pancreas recover?

Weight loss is required for remission, but it isn't enough by itself. You need to still have a functioning pancreas, and the potential for your beta cells (cells within the pancreas) to recover. A research paper on cell metabolism explains that: "Substantial weight loss can reverse the process underlying type 2 diabetes. Liver fat content and pancreas fat content decreased in all. Return to non-diabetic glucose control depends upon beta cell ability to recover." (source - pg1).

This is why you have a better chance of remission if you lose weight soon after diagnosis: your pancreas has probably taken less damage.

How can I improve my chances of remission?

  1. Lose weight as soon as possible after diagnosis. This gives your pancreas the best chance of recovering. However, at least one person who had diabetes for 28 years has achieved remission (source stating the 28yr person - scientifict paper - pg6. More comprehensible sources about short vs long duration diabetes: slide no.26 and no.27, or about 34-35 minutes into this video)).
  2. Best results are seen if you lose 20% or more of your body weight (source - slide no.34, or about 35-36 minutes into this video). This means if (like me) you're obese, you may have to lose more than 15kg / two and a half stone. So, if it hasn't completely worked after the initial 8-12 weeks, consider continuing to gradually lose weight for a while longer.

Is it worth doing the diet, given the chances of remission aren't that high?

This is a personal choice, but I would suggest it is, because:

  • Even if your pancreas can't recover, losing fat around your liver may still improve insulin and glucose control somewhat. Your liver produces glucose, and thus "decreasing the fat content of liver can improve insulin suppression of glucose production and improve fasting glucose." (source - pg2).
  • If you're seriously overweight, losing fat can have other health benefits.

What happens if I eat normally after going into remission?

In theory, if you've achieved substantial pancreas recovery, you should be able to eat fairly normally (as long as you keep the weight off). If your pancreas is still struggling, you may still need to watch your carbs.

I'm struggling to find detailed information on people's diets after remission. However, the key, as always, is to test: eat, test your post-prandial sugars, test your fasting sugars. If fasting sugars stay below 7mmol/l, and your HbA1C stays good, then presumably your diet is ok for your level of pancreas functionality and insulin sensitivity.

Am I still diabetic after remission? Do I need to keep going for checkups?

Yes. And no. This is complicated. Some people talk about reversing diabetes, suggesting a full cure. Others about remission, suggesting it can come back. Remission is probably the better term: if you regain the weight, it will come back. Additionally, this is relatively new research. It's always possible that even if your pancreas recovers well, it's still suffered enough wear and tear to lead to issues many years in the future.

This is why it's important to continue going for checkups (HbA1C tests, retinopathy scans, and so on), and monitoring your fasting glucose.

Can this diet help type 1 diabetics?

No. Type 1 and type 2 diabetes are very different diseases. In type 1, the immune system attacks the pancreas, killing beta cells. This cannot be fixed with weight loss.

What are the side effects of the diet?

The possible side effects will be similar to any low calorie diet, such as those described on the NHS very low calorie diets page.

  • Hunger (in the case of this diet, this should ease after the first day or two)
  • Low energy
  • Dry mouth
  • Risk of constipation or diarrhoea
  • Headaches
  • Dizziness
  • Cramps
  • Thinning hair (it should grow back)

Professor Roy Taylor also mentions:

  • Feeling cold as a possible side effect (pg189 Life Without Diabetes).
  • The social aspect: that invitation to a friend's BBQ is now a source of stress rather than joy.

In my annecdotal experience from the Newcastle Diet in 2021:

  • Hunger, headaches, dizziness/shakey-ness, feeling cold - but only for the first day or two. Headaches only returned later if I didn't drink enough.
  • Dry mouth - but that made drinking plenty easier and wasn't too bothersome.
  • The digestive system does not like this diet, and will act out in different ways each day.
  • Low energy: lots of people report good energy levels on this diet. I was not one of them.
  • Worse premenstrual symptoms: again, this is my annecdotal evidence, and I haven't found it mentioned anywhere else. I usually experience a slight energy dip a couple of days before my period. This time, it felt like someone had come along and ripped my batteries out. It turns out, there may be actual science for this - it's possible women burn more calories between ovulation and period, peaking a couple of days before the period, and then declining again. So my calorie deficit will have been even more severe at that point.
  • Lighter period: when trying the Newcastle diet, my period spent several days being very light, as if it was trying to start properly but couldn't really. This immediately fixed itself when I stopped the diet (see Day 19 and Weeks 4-12).
  • The social aspect was less of an issue than it might have been (thanks COVID), but it still popped up a couple of times. In retrospect, I wish I'd really planned in advance how to handle this.
  • There's an emotional aspect: I comfort eat. That's how I got in this state in the first place. Removing my go-to coping mechanism for weeks on end was not fun! The fact it was time-limited did help though.