Meanwhile skimmed milk can make it harder to keep the pounds off, according to the doctor behind the Fast 800 Diet. He explains how your milk choice, whether it's plant-based or dairy, affects your weight and health

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With Veganuary barely behind us, many of us might be thinking about continuing some of our plant-based resolutions. According the Veganuary charity, which encourages people to go plant-based for a month the primary reason for joining the challenge is health (46 per cent of people said this was their main reason, 34 per cent animal welfare and 12 per cent environment). But how healthy is it long term? We asked Dr Michael Mosley, creator of the 5:2  and Fast 800 intermittent fasting diets and the Fast800 online programme to delve into one food group in particular – dairy. Environmental reasons aside, are we missing out on key health benefits by choosing plant milks over dairy? And if we go all-in-for cow’s milk, which version is best?

GTG: We seem to be cutting out dairy more than ever...

MM: “Yes. Britons are drinking a third less milk than they were 30 years ago, and consumption rates continue to fall. A recent survey found a third of people under 35 are now considering cutting back on dairy, citing health or moral reasons. Instead, they opt for plant-based alternatives such as soya , almond or coconut ‘milk’. My 18-year-old daughter Kate is one of them. Cow’s milk makes her uncomfortable and bloated, so in a bid to reduce her symptoms, she made the switch to almond milk .

“Kate’s problem is surprisingly common. About 60 per cent of the global population lack the enzyme lactase that helps us digest the sugars in cow’s milk, called lactose. For these people, guzzling milk can lead to unpleasant symptoms such as stomach irritation, gas and bloating. However, the vast majority have minor symptoms and even those with severe lactose intolerance can usually tolerate a tiny splash in their tea.

“But for some people, even the odd builder’s tea can cause crippling stomach cramps, not to mention embarrassing wind. So I understand why the alternative milk market is booming. But I also have concerns.

What concerns you about plant milks?

“If you are thinking of switching away from dairy, for moral or environmental reasons, fine. If it’s for health reasons, then be aware that cow’s milk has higher levels of many nutrients than plant milks, including calcium and iodine, which are important for healthy bones and an active thyroid. And not all plant milks are fortified to make up for the gap. If you are trying to be especially healthy or environmentally aware by buying organic plant milks, be warned these cannot be fortified to qualify as organic. Plus rice milks contain high levels of arsenic and aren’t suitable for young children.

So is skimmed milk a healthy choice?

“Not entirely. If you are thinking of switching to skinny versions, be warned: they could make you fatter. After weighing up the evidence, I’ve recently switched to the full-fat variety again – and after reading this you may want to do the same.

Why have we been told to avoid full-fat milk?

“One of the reasons is because it contains saturated fats and these are supposed to be bad for us. But it turns out that the fats you find in full-fat milk may be protective.

“In a recent study researchers measured blood levels of common dairy fats in nearly 3,000 middle-aged Americans. They were then followed for 22 years. At the end of that time, the researcher discovered that the participants with the highest levels of dairy fats in their blood had the lowest risk of death from heart disease. They were also 42 per cent less likely to have died from a stroke. The researchers concluded that the sort of fats you find in full fat milk seem to be beneficial rather than harmful.”

But surely full-fat milk makes you fat?

“It’s been assumed that because skimmed milk has less than two-thirds of the calories of full-fat milk, it must be less fattening. But this ignores the fact that when you drink full-fat milk it reduces your appetite much more effectively than drinking skimmed milk, so you are less likely to snack later.

“There have been a number of recent studies showing that full-fat milk drinkers tend to be slimmer and have a lower risk of raised blood pressure and blood sugars than those who drink skimmed milk.

“A recent study of 1,600 healthy middle-aged Swedish men, for example, found those who ate butter and drank full-fat milk were half as likely, over the 11-year study period, to become obese than those who went for skimmed milk and low-fat spreads.

“And a study of 18,438 American women found those eating the highest amount of full-fat dairy were the least likely to gain a lot of weight over 11 years.”

So why not just go for semi-skimmed milk?

“Well, you certainly could but it has lower levels of essential fatty acids, such as omega-3, which are linked to improved cognition and reduced anxiety and depression.

“Full-fat milk contains 90 times the amount of omega 3 fats you’d find in skimmed milk and twice as much as you’d find in semi-skimmed. Turning full fat into skimmed milk also involves removing a host of fat-soluble vitamins, such as vitamin A and vitamin D. Some of these vitamins are added back in afterwards, but by no means all.

“I like the flavour of full-fat milk and those extra few grams of fat curb my hunger pangs.”

How much dairy milk do we need in our diet?

"There are no recommended levels of dairy for teenagers or adults, however, the NHS recommends that you give your child at least 350ml (12oz) of milk a day, or two servings of foods made from milk, such as cheese, yoghurt or fromage frais. That will provide around 350mg of calcium a day

“Skimmed or 1 per cent fat milk doesn't contain enough fat, so isn't recommended for children under 5.

“Do not give young children rice milk because of the high levels of arsenic they contain."

What's the best plant-based milk alternative?

“The plant-based milk that is good for you and best for the planet is probably oat milk. Unlike almonds or soya, growing oats doesn’t do much environmental damage. Because it is fortified it is an excellent source of many vitamins and minerals. It also contains a type of fibre, beta-glucans, that has been shown to reduce cholesterol.”

The Fast 800  is an approach to healthy living and weight loss based on the latest scientific research. The Fast 800 online programme has been developed in conjunction with Dr Michael Mosley for those that need more support and guidance for achieving long-lasting health.