Successful Weight Loss — Part 2: Caveats of the Weight Loss Diets

By a Lifestyle Medicine Physician

This article follows on from

‘Successful Weight Loss — Part 1: Which Diets Work?’.

In that article I outlined the Ketogenic diet, Low Calorie Diet and Whole Food Plant Based Diets.

If you don’t know much about the different diets, have a read of that article first before reading my comparison of them in this article.

What are the Caveats of the various dietary patterns if you’re thinking of weight loss?

1) Adherence

Ultimately, whilst all of these diets will help you lose weight, keeping the weight off comes down to whether you stick to the diet.

Hence the classic, and seemingly endless cycle of yo-yo dieting.

Why people stick with a diet has been well studied, and it comes down to two things:

(a) how easy or hard the diet is, and

(b) the motive for being on the diet

For example, a calorie restriction diet is often hard to maintain for weight loss. But there are people who eat a calorie restricted diet lifelong for health benefits such as its effect on prolonging healthy lifespan.

A recent study compared the dietary adherence of 5 types of ‘restrictive’ dietary groups: Vegetarians, Vegans, Gluten-free, Paloelithic and Weight Loss dieters.

They found that adherence was greatest amongst Vegans and lowest amongst Weight Loss dieters.

Although they compared the personal characteristics of each group, they found that the real key to dietary adherence was down to motive for dietary choice.

Vegetarians and Vegans tended to identify more with their diets within a greater social and ethical framework — so one that went beyond just the individual.

Both the ‘gluten-free’ and ‘Paleo’ diet groups seemed to be predominantly motivated by individual health — the lower adherence of the ‘gluten free’ group (which included both confirmed Coeliac as well as people who reported an intolerance) was a surprise to the researchers.

Lowest adherence was within the ‘weight-loss’ diet group.

The researchers concluded that ‘positive diet-based identities’ are more likely to result in adherence*.

In other words, if your diet feels that it is a part of who you are — and it has a positive emphasis — then you are very likely to maintain it long-term.

2) Slimmer — but at what cost?

I would argue that you could technically follow any one of these diets and eat poorly. You could be vegetarian or vegan and consume nothing but chips and sugary drinks. People do!

Whilst the low-carb ketogenic diets have revolutionised life for people with intractable epilepsy, in reality we don’t know much about the long-term effects on adults.

Studies on epileptic children have shown a significant rise in fracture risk over time with those on ketogenic diets because the calcium in bone is used to buffer the rise in acid in the blood from ketone bodies.

There also appears to be a rise in LDL-cholesterol and calcification of arteries over time which suggest that there may be a cardiovascular risk long-term with this diet.

We know that the WHO has classified red meat as a probable carcinogen and processed meat as a definite carcinogen, so whether this diet would increase cancer risk also remains an unknown.

What’s more our gut microbiota needs fibre (which is only found in plants) to remain healthy, and we are uncovering our microbiota’s role in immunity and health every day.

A meta-analysis (putting all the studies on this together to get a really large pool of data) looked at low and high carbohydrate diets. What they found was that when carbohydrate was exchanged for animal protein or fat, mortality increased significantly (by 17–31%). When carbohydrate was exchanged for plant protein or fat (eg higher nuts, wholegrain intake) mortality fell by 8–21%.

We don’t yet know the full answer to all the questions about this diet. But if you’re looking to lose weight, point 3 below may be the real clincher.

3) Do you want to lose FAT, WATER or MUSCLE on a weight loss diet?

This may seem like an insane question.

Obviously the answer is FAT!

But, in fact we know very well that each of the above diets has a different way to drop those pounds.

A recent study pitted a whole food plant based diet (WFPBD) against a ketogenic diet.

They kept 20 subjects for 4 weeks at the Metabolic Unit at the National Institute of Health in the US. For the first 2 weeks half were fed a Keto diet and the other half was fed the WFPB diet. After 2 weeks they swapped them over. The subjects could eat as much as they liked, as long as they stuck to the dietary pattern they were assigned each fortnight. They weren’t actually asking them to lose weight.

In the first week the Keto diet group got off to a great start with losing weight, but by the second week this was plateauing.

The WFPBD group were slower off the mark, but approached the Keto group by the end of the second week.

There was no significant difference in weight loss between the two diets.

But when they did detailed body compositions scans what they found was this: The Keto group lost predominantly water and muscle. They didn’t lose any significant fat! During the first week of the Keto diet, they would have used up any stored glucose. Glucose is stored as glycogen in the body. Each glycogen molecule is bound to 3 molecules of water, so as it is broken down and used up, water is released…and then it is peed!

Hence the rapid weight loss in week 1. After that, they lost muscle.

The WFPBD however only lost fat.

Apart from the obvious desire to lose fat rather than muscle or water, this is significant for another two reasons if you want to maintain weight loss.

a) fat that is stored around your organs makes you more fat. This ‘visceral’ fat releases hormones that make you more insulin resistant. The more insulin resistant you are the more fat you store.

You see how this is a frustrating vicious cycle?

b) muscle is critical to soak up the glucose in your blood and stop it getting stored as fat.

So you see, losing fat is important for ensuring you keep those pounds off!

What about calorie restriction?

A study in overweight and obese people who undertook calorie restriction (25% fewer calories per day for 12 weeks) found that whilst the majority of their weight loss was fat loss, approximately 12% of their weight loss wasn’t. So not bad!

A review of weight loss interventions found that in fact the greater the degree of calorie restriction, the less the percentage of fat loss.

Bear in mind, whilst the way you eat is critically important to maintaining a healthy weight, we know that sleep, stress and exercise play a vital role too.

I’ll include more on these soon!

Coming soon: my article ‘Be selfish …. and save the world’ for some great motivation to stick with a WFPB dietary pattern!