Nutritionist Rob Hobson sets straight some common misconceptions about what a healthy diet is and isn’t – including those even we believed!

I wanted to set the record straight about a number of common food and nutrition myths that frequently make the headlines – and that many of my clients believe. In some cases the facts are just wrong and for others they may not be as straight forward as previously thought. Either way, it’s interesting to separate the science from the hype, and researching some of these myths has answered a few of the questions that have been niggling at me for a while now.

1. Foods naturally high in cholesterol such as eggs can raise blood cholesterol, increasing your risk of heart disease

Previous advice to limit your intake of eggs has since been changed as we now know foods naturally high in cholesterol have very little impact on levels in the blood. However, those with diabetes or familial hypercholesterolaemia you should still limit eating them to three times across the week. Eggs are super nutritious providing a wide spectrum of nutrients and have even been shown to aid weight loss when eaten for breakfast.

It’s saturated fat in the diet that increases cholesterol and leads to heart disease

The topic of fats is the most complicated of all the nutrients. Worldwide health advice has been based around the reduction of saturated fat in the diet to help maintain healthy cholesterol levels, which is associated with heart disease risk. However, research has suggested saturated fat intake may not be as strongly linked to heart disease as previously thought.

So, quick lessen in cholesterol; Firstly, cholesterol is not all bad and has many important functions in the body. Secondly, the body produces more cholesterol than you eat and controls levels in a highly regulated process.

When you eat food, the body breaks down carbs and proteins for energy, some of which is used immediately, some is stored (such as glycogen in muscles) and the remainder is converted to triglycerides (fat) and cholesterol by the liver.

Oil and water don’t mix, so the liver packages fats (oil) together with protein and cholesterol in a phospholipid shell allowing them to be transported in the blood (water). Whilst saturated fat increases levels of Low Density Lipoprotein of LDL (bad) cholesterol in the body, it also produces High Density Lipoprotein or HDL (good) cholesterol, which has a protective effect by reducing harmful LDL.

But it’s not all to do with saturated fat intake and research suggests LDL may not be as harmful as another type of cholesterol known as Very Low-Density Lipoprotein) or VLDL, which is easily oxidised in the body making it especially harmful to arteries, increasing the risk of heart disease.

VLDL contains a much greater concentration of triglycerides (fats) than LDL so reducing levels of triglycerides by watching your intake of high GI foods such as sugar and highly processed grains (such as white flour) is just as important if not more so than saturated fat.

In a nutshell, eating an appropriate amount of calories from a diet free of too many processed foods that includes plenty of veggies, lean proteins, healthy fats and higher fibre grains and pulses is a good approach.

You shouldn’t eat after 7pm as food is stored as fat

Firstly, the body doesn’t suddenly decide to turn food eaten after 7pm into fat. Secondly, although your metabolism may slow down as you sleep, it still continues to digest any food in the gut. The amount of fat you lay down is determined by the excess amount of calories you eat during the day against those you use up by keeping active.

This tip may be useful for weight loss but only by preventing people from overeating at night and so reducing their overall calorie intake.

4. All Carbohydrates make you fat

Yes and no. Nutritionally, there is nothing fattening about complex carbs with a low GI, such as oats, wholegrain rice or wholemeal pasta, which contain 4 calories per gram (the same as protein). When eaten in sensible portion sizes, these foods are a rich source of nutrients such as fibre and B vitamins (used to covert food into energy) and have less impact on blood sugar levels than their high GI counterparts. However, what you choose to put on these foods will only add to their calorie count and it’s worth mentioning that an excess of any food will potentially encourage weight gain. ​Not all carbs are the same though, and sticking to fibre-rich, carbs with a low GI, will fill you quicker (with more nutrients) on smaller portions than opting for carbs with a high GI such as sugar, which are easy to over consume and instigate insulin spikes that can encourage the storage of fat as well as put you at risk of diseases such as heart disease when eaten in excess. fibre-rich, carbs with a low GI, will fill you quicker

Cutting back on carbs and opting for small servings of Low GI varieties whilst increasing protein does appear to be a useful weight loss strategy (protein and high fibre carbs are very filling when served together), especially for people who find it difficult to stay in control when eating carbohydrate-rich foods but there is not reason to completely remove all carbohydrate foods from your diet.

5. Raw food diets are better for your health as they’re rich in enzymes that are essential for healthy digestion

Raw foods are highly nutritious and a great addition to the diet but many of the reasons given for the benefit of a raw food diet don’t quite add up. There are also several antioxidants made more available in foods when cooked such as lycopene (found in red veggies) and beta-carotene (found in orange and dark green veggies).

Raw foodies frequently talk of beneficial enzymes found in raw foods but these are necessary for plant survival and not essential for human health. This diet is also claimed by some to preserve the ‘finite’ number of enzymes found in the body by supplying them in raw food. However, without enzymes we couldn’t function as they act as catalysts for the many chemical reactions that take place so the body, which continues to make them throughout life meaning we’re never in short supply.

Raw foodies usually talk about how great they feel but much of this can also be attributed to the healthy lifestyle that usually accompanies this way of eating that often involves regular exercise and abstaining from alcohol, coffee and smoking.

Whilst the fact that enzymes denature above a certain temperature (cooking) is true, they are proteins and are destroyed by stomach acids anyway once the food is eaten (some enzymes found in foods such as kimchi may reach the gut but their benefit is likely to be minimal).

Raw foodies usually talk about how great they feel but much of this can also be attributed to the healthy lifestyle that usually accompanies this way of eating that often involves regular exercise and abstaining from alcohol, coffee and smoking.

Having said all this, there are many unhealthier ways to eat than a diet of raw unprocessed foods.

Bread causes bloating

Putting gluten-sensitivity and coeliac disease aside, some people are sensitive to wheat, which may cause bloating. However, sensitivity is not that common and wheat allergy is rare. There is also no diagnostic test for wheat sensitivity and treatment involves an exclusion diet.

Research investigating the effects of eating bread found that bloating was less when compared with pasta. Research also showed that 1 in 5 Brits believed they would benefit from avoiding bread and 5% claimed to be gluten intolerant (actually affects about 0.5% of the population). It’s also thought that bloaters are more sensitive to the feeling of abdominal gas whilst not actually producing more of it.

Other factors can also be responsible for bloating such as IBS, skipping meals, constipation, a lack of good bacteria in the gut and foods rich in fermentable carbohydrates such as onions, artichokes and leek

Other unproven theories linking bread to bloating include the baking method (Chorleywood process of skipping the second rising) and yeast, which is actually deactivated during the baking process.

Other factors can also be responsible for bloating such as IBS, skipping meals, constipation, a lack of good bacteria in the gut and foods rich in fermentable carbohydrates such as onions, artichokes and leeks. A sudden increase in dietary fibre can also cause bloating so should be done gradually. Opting for toasted bread and speciality loaves such as sourdough can reduce bloating in those sensitive to wheat.

The trend for gluten-free diets has had a big impact on attitudes towards bread and other carbohydrate foods resulting in people unnecessarily cutting out food groups, which in some cases may lead to nutrient imbalances. In the UK, bread contributes to 1/5 of the calcium and magnesium intake as well as 15% of iron and 20% of fibre.

The only way to actively boost your metabolism is with regular exercise and those with a greater ratio of muscle to fat tend to have a higher metabolic rate

Frequently eating small meals throughout the day can increase your metabolism and help you to lose weight

It’s true that your metabolism increases slightly as you eat but not enough to cause any significant weight loss. Snacking is often used by dieters as way of avoiding hunger pangs but the downside is that any meal occasion has the potential for overeating.

The only way to actively boost your metabolism is with regular exercise and those with a greater ratio of muscle to fat tend to have a higher metabolic rate.

You need to include dairy foods in your diet to get enough calcium

Most people are well versed in the importance of eating foods rich in calcium to maintain healthy bones but this doesn’t mean relying solely on dairy foods. Many people these days choose not to eat dairy foods, although cutting them from the diet isn’t necessary or of particular benefit to health unless you have an intolerance.

Whilst dairy foods do provide a readily available source of calcium, other foods rich in this mineral include dark green veggies (especially kale), almonds, tofu, fortified plant milks and ground spices. Including 4 servings each day will supply your RDA for calcium.

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Nutritionist Rob Hobson runs consultancies RHNutrition and HOPE (Helping Older People to Eat Well) and has built a reputation as a trustworthy and inspirational source of information working for the NHS, private clients and leading food and nutrition companies including supplements provider Healthspan. An obsessed foodie and skilled cook, Rob regularly cooks for celebrity clients and contributes to national press including Stella, Daily Mail, Grazia, Harpers Bazaar, Runners Fitness, Healthy magazine and Women’s Health.