Click to read Can Type 2 Diabetes be Reversed
Click to read Very Low Calorie Diets & Type 2 Diabetes Reversal Part 1: Blood Glucose
Click to read Very Low Calorie Diets & Type 2 Diabetes Reversal Part 2: Insulin
Click to read Very Low Calorie Diets & Type 2 Diabetes Reversal Part 3: The Liver & Pancreas
Click to read Very Low Calorie Diets & Type 2 Diabetes Reversal Part 4: Glucose Tolerance
So we've seen that very low calorie diets can bring about rapid improvements in fasting blood glucose and insulin, the liver's response to insulin, and the function of the pancreas in terms of its release of insulin.
We've also seen that maintaining these changes using the commonly prescribed low fat high carbohydrate diet alludes the majority of people, but by no means everyone.
Over the last two weeks we looked at the importance of liver and pancreas fat to put things into a clearer more useful context. Click here if you haven't read that article yet.
This week we're going to look at some important benefits of very low calorie diets in terms of blood pressure, the heart, and blood lipids (e.g. cholesterol). Because, let's face it, if you have type 2 diabetes or are well on your way to having it, some or all of these are also likely to be important to you.
Type 2 diabetes and hypertension (high blood pressure) often go hand-in-hand.
One explanation for this link is that the hormones insulin, leptin, and aldosterone are elevated in type 2 diabetes, and these same hormones increase the activity of our sympathetic nervous system – that’s the part responsible for our stress or fight or flight response – which increases things like heart rate and blood pressure (1,2).
Having chronically or frequently high blood pressure is tough on our blood vessels, and is unsurprisingly linked to heart disease and risk of stroke.
Given the link between insulin and blood pressure, and that we learned in part 2 and part 3 about reductions in insulin and insulin resistance, it’s unsurprising that very low calorie diets often lead to reductions in blood pressure (3,4).
The reductions in blood pressure were consistent with what normally would require one or more blood pressure lowering medications and resulted in some volunteers coming off their medication (3,4).
You can see specific results by downloading Table 5 as a pdf here (3-9).
Very low calorie diets consistently resulted in reductions of both systolic and diastolic blood pressure – that’s the bigger first number and the smaller second number that you get when measuring blood pressure, respectively.
The size of the reduction varied across studies, probably due to differences in starting values, diet duration, and degree of weight reduction.
So not only did insulin and blood glucose related measures tend to normalise, but blood pressure also often fell back into the normal range following very low calorie diets.
In one study that retested people 18 months after the very low calorie diet finished, blood pressure and heart rate went back up along with an increase in weight and fasting blood glucose (3).
However, in another study, one that involved some basic instructions on how to eat after the very low calorie diet, the improvements in blood pressure and the reduction in bodyweight were maintained (6).
The lesson once again being that the positive effects of the diet are largely undone by weight regain.
It’s worth mentioning that blood pressure changes rapidly all the time. When you get up out of a chair, your blood pressure should go up to compensate, when it doesn’t adjust fast enough you get light-headed.
When we talk about a long-term change, we mean blood pressure measured at more or less the same time of day under resting, often seated, conditions, and following five or so minutes of inactivity.
Heart Form and Function
One of the problems of having type 2 diabetes is that it leads to changes in the heart, some are more structure and some more function (10).
One of the things that often happens to the heart in type 2 diabetes is the left ventricle thickens (see image below).
So in addition to reducing fat in the liver and in the pancreas (see Part 3), very low calorie diets can reduce fat in the heart (11).
Interestingly, these changes were still there 18 months after the diet despite partial weight regain and associated worsening of glucose control (3).
Some of the people in this study (5 out of 14) also followed an exercise programme during the very low calorie diet, and although the authors of the study say this had no effect, it isn’t clear how they tested whether or not it did (3), so I’m inclined to think it may have helped a little too.
Blood lipids are the collective term for things like cholesterol and triglycerides. In terms of common blood tests your doctor might order these include: total cholesterol, low-density lipoprotein cholesterol (LDL), high-density lipoprotein (HDL), and triglycerides (sometimes also called triacylglycerols).
A few things worth noting are that LDL is usually estimated, not directly measured. That means that it’s not always accurate. Also worth noting is that both LDL and HDL come in different ‘flavours’, and those ‘flavours’ have different implications for health.
The blood lipids that are commonly measured actually don’t give the most valuable information when it comes to health, but that’s a whole blog series on its own.
However, what is measured and reported in the majority of studies, including the ones reviewed in this article, is the same thing that is commonly measured when you get your checkup.
You can see specific results by downloading Table 6 as a pdf here (4,6,8,9,11,13-20).
The most consistent finding, and also the one with the largest change was a reduction in fasting triglycerides. That’s good news as high triglycerides show the body is not dealing well with fat (more on this in future posts).
Estimates of LDL-cholesterol generally went down or didn’t change. None of the studies looked beyond simply LDL-cholesterol concentration, so we don’t know if there were changes to the nature of the cholesterol.
Finally, HDL tended to remain the same or even go down slightly. This is likely due to the low fat, and at least in relative terms, high carbohydrates content of most of the diets used (21).
One study that does not appear in Table 6 because the results were represented in graphs rather than providing exact numbers for me to add to the table, compared higher carbohydrate/lower fat with lower carbohydrate/higher fat diets, and, as expected, found HDL increased in the latter group (22).
You may be wondering what happened long-term. When it comes to cholesterol there is no long-term as blood cholesterol is highly responsive to diet, and changes measurably within days of a change to diet or weight. In the case of triglycerides, you even get changes after a meal, which is why these measures are traditionally done after an overnight fast.
I said it in an earlier blog, but this bares repeating – if you are planning on trying to reverse your type 2 diabetes, partly or fully, with diet and/or exercise, let your medical care team know so they can monitor you and adjust your medication.
If you’ve read this miniseries of articles and taken most of it onboard, you’ll remember that dietary changes can drastically reduce blood glucose, insulin needs, and blood pressure. In practice this means that some or all of the medications/insulin you are on will need adjusting so you don’t end up with dangerously low blood glucose or blood pressure.
Also, the diets in the studies we’ve been looking into were specially formulated to make sure they provided enough of the essentials like vitamins and minerals. Simply working out a diet with 400-1000 kcal/day isn’t going to ensure you get what you need.
Take home messages from this series
Very low calorie diets can have a profound effect on the processes underlying type 2 diabetes. These include insulin production and insulin resistance, which together add up to better glucose control, but extend much further into improvements in blood pressure, heart health and fat metabolism.
That can translate into a reversal of the symptoms for many, and a substantial reduction in the need for insulin and/or medication in others. Either way that translates into better health and function, and probably substantial financial savings.
The benefits are largely dependent on the weight reduction achieved then being maintained. For more explanations on why, check out Is type 2 diabetes all about the fat?.
What all this means is that while very low calorie diets offer a fairly rapidly acting means to reverse type 2 diabetes, they are not a ‘cure’.
To look for a one-off ‘cure’ for type 2 diabetes is to misunderstand the condition. This was the topic of the very first blog post: The Cure for Type 2 Diabetes is a Change in Perspective.
Type 2 diabetes is a physiological state that you can move in and out of. A good way of thinking about it is as a repetitive strain injury to our metabolism.
What that means is that to reverse type 2 diabetes permanently you need a long-term plan, whether or not that involves very low calorie diets at one or more points.
In future weeks we’ll look at other less drastic dietary options with a bigger safety margin. If you can’t wait and want to try a very low calorie diet, please seek professional help.
But for the next few weeks we’ll look at the central importance of exercise in helping improve glucose control along with other aspects of health. You’ll find that over in the MOVE blog here.
References: click here for a full list of references cited.
To learn more about type 2 diabetes and what you can do to better manage, and often reverse it, watch my free video education series. If you want one-on-one help dealing with your type 2 diabetes, contact me here to book a consultation.