Robert F. Kennedy Jr, the United States’ top public health official, recently claimed some religious groups avoid the measles, mumps and rubella (MMR) vaccine because it contains “aborted fetus debris” and “DNA particles”.

The US is facing its worst measles outbreaks in years with nearly 900 cases across the country and active outbreaks in several states.

At the same time, Kennedy, secretary of the Department of Health and Human Services, continues to erode trust in vaccines.

So what can we make of his latest claims?

There’s no fetal debris in the MMR vaccine

Kennedy said “aborted fetus debris” in MMR vaccines is the reason many religious people refuse vaccination. He referred specifically to the Mennonites in Texas, a deeply religious community, who have been among the hardest hit by the current measles outbreaks.

Many vaccines work by using a small amount of an attenuated (weakened) form of a virus, or in the case of the MMR vaccine, attenuated forms of the viruses that cause measles, mumps and rubella. This gives the immune system a safe opportunity to learn how to recognise and respond to these viruses.

As a result, if a person is later exposed to the actual infection, their immune system can react swiftly and effectively, preventing serious illness.

Kennedy’s claim about fetal debris specifically refers to the rubella component of the MMR vaccine. The rubella virus is generally grown in a human cell line known as WI-38, which was originally derived from lung tissue of a single elective abortion in the 1960s. This cell line has been used for decades, and no new fetal tissue has been used since.

Certain vaccines for other diseases, such as chickenpox, hepatitis A and rabies, have also been made by growing the viruses in fetal cells.

These cells are used not because of their origin, but because they provide a stable, safe and reliable environment for growing the attenuated virus. They serve only as a growth medium for the virus and they are not part of the final product.

You might think of the cells as virus-producing factories. Once the virus is grown, it’s extracted and purified as part of a rigorous process to meet strict safety and quality standards. What remains in the final vaccine is the virus itself and stabilising agents, but not human cells, nor fetal tissue.

So claims about “fetal debris” in the vaccine are false.

It’s also worth noting the world’s major religions permit the use of vaccines developed from cells originally derived from fetal tissue when there are no alternative products available.

Are there fragments of DNA in the MMR vaccine?

Kennedy claimed the Mennonites’ reluctance to vaccinate stems from “religious objections” to what he described as “a lot of aborted fetus debris and DNA particles” in the MMR vaccine.

The latter claim, about the vaccine containing DNA particles, is technically true. Trace amounts of DNA fragments from the human cell lines used to produce the rubella component of the MMR vaccine may remain even after purification.

However, with this claim, there’s an implication these fragments pose a health risk. This is false.

Any DNA that may be present in this vaccine exists in extremely small amounts, is highly fragmented and degraded, and is biologically inert – that is, it cannot cause harm.

Even if, hypothetically, intact DNA were present in the vaccine (which it’s not), it would not have the capacity to cause harm. One common (but unfounded) concern is that foreign DNA could integrate with a person’s own DNA, and alter their genome.

Introducing DNA into human cells in a way that leads to integration is very difficult. Even when scientists are deliberately trying to do this, for example, in gene therapy, it requires precise tools, special viral delivery systems and controlled conditions.

It’s also important to remember our bodies are exposed to foreign DNA constantly, through food, bacteria and even our own microbiome. Our immune system routinely digests and disposes of this material without incorporating it into our genome.

This question has been extensively studied over decades. Multiple health authorities, including Australia’s Therapeutic Goods Administration, have addressed the misinformation regarding perceived harm from residual DNA in vaccines.

Ultimately, the idea that fragmented DNA in a vaccine could cause genetic harm is false.

The bottom line

Despite what Kennedy would have you believe, there’s no fetal debris in the MMR vaccine, and the trace amounts of DNA fragments that may remain pose no health risk.

What the evidence does show, however, is that vaccines like the MMR vaccine offer excellent protection against deadly and preventable diseases, and have saved millions of lives around the world.

Hassan Vally, Associate Professor, Epidemiology, Deakin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

It’s a well-known fact that to lose weight, you either need to eat less or move more. But how many calories do you really need to cut out of your diet each day to lose weight? It may be less than you think.

To determine how much energy (calories) your body requires, you need to calculate your total daily energy expenditure (TDEE). This is comprised of your basal metabolic rate (BMR) – the energy needed to sustain your body’s metabolic processes at rest – and your physical activity level. Many online calculators can help determine your daily calorie needs.

If you reduce your energy intake (or increase the amount you burn through exercise) by 500-1,000 calories per day, you’ll see a weekly weight loss of around one pound (0.45kg).

But studies show that even small calorie deficits (of 100-200 calories daily) can lead to long-term, sustainable weight-loss success. And although you might not lose as much weight in the short-term by only decreasing calories slightly each day, these gradual reductions are more effective than drastic cuts as they tend to be easier to stick with.

Hormonal changes

When you decrease your calorie intake, the body’s BMR often decreases. This phenomenon is known as adaptive thermogenesis. This adaptation slows down weight loss so the body can conserve energy in response to what it perceives as starvation. This can lead to a weight-loss plateau – even when calorie intake remains reduced.

Caloric restriction can also lead to hormonal changes that influence metabolism and appetite. For instance, thyroid hormones, which regulate metabolism, can decrease – leading to a slower metabolic rate. Additionally, leptin levels drop, reducing satiety, increasing hunger and decreasing metabolic rate.

Ghrelin, known as the “hunger hormone”, also increases when caloric intake is reduced, signalling the brain to stimulate appetite and increase food intake. Higher ghrelin levels make it challenging to maintain a reduced calorie diet, as the body constantly feels hungrier.

Insulin, which helps regulate blood sugar levels and fat storage, can improve in sensitivity when we reduce calorie intake. But sometimes, insulin levels decrease instead, affecting metabolism and leading to a reduction in daily energy expenditure. Cortisol, the stress hormone, can also spike – especially when we’re in a significant caloric deficit. This may break down muscles and lead to fat retention, particularly in the stomach.

Lastly, hormones such as peptide YY and cholecystokinin, which make us feel full when we’ve eaten, can decrease when we lower calorie intake. This may make us feel hungrier.

Fortunately, there are many things we can do to address these metabolic adaptations so we can continue losing weight.

Weight loss strategies

Maintaining muscle mass (either through resistance training or eating plenty of protein) is essential to counteract the physiological adaptations that slow weight loss down. This is because muscle burns more calories at rest compared to fat tissue – which may help mitigate decreased metabolic rate.

Gradual caloric restriction (reducing daily calories by only around 200-300 a day), focusing on nutrient-dense foods (particularly those high in protein and fibre), and eating regular meals can all also help to mitigate these hormonal challenges.

But if you aren’t someone who wants to track calories each day, here are some easy strategies that can help you decrease daily calorie intake without thinking too much about it:

1. Portion control: reducing portion sizes is a straightforward way of reducing calorie intake. Use smaller plates or measure serving sizes to help reduce daily calorie intake.

2. Healthy swaps: substituting high-calorie foods with lower-calorie alternatives can help reduce overall caloric intake without feeling deprived. For example, replacing sugary snacks with fruits or swapping soda with water can make a substantial difference to your calorie intake. Fibre-rich foods can also reduce the calorie density of your meal.

3. Mindful eating: practising mindful eating involves paying attention to hunger and fullness cues, eating slowly, and avoiding distractions during meals. This approach helps prevent overeating and promotes better control over food intake.

4. Have some water: having a drink with your meal can increase satiety and reduce total food intake at a given meal. In addition, replacing sugary beverages with water has been shown to reduce calorie intake from sugars.

4. Intermittent fasting: restricting eating to specific windows can reduce your caloric intake and have positive effects on your metabolism. There are different types of intermittent fasting you can do, but one of the easiest types is restricting your mealtimes to a specific window of time (such as only eating between 12 noon and 8pm). This reduces night-time snacking, so is particularly helpful if you tend to get the snacks out late in the evening.

Long-term behavioural changes are crucial for maintaining weight loss. Successful strategies include regular physical activity, continued mindful eating, and periodically being diligent about your weight and food intake. Having a support system to help you stay on track can also play a big role in helping you maintain weight loss.

Modest weight loss of 5-10% body weight in people who are overweight or obese offers significant health benefits, including improved metabolic health and reduced risk of chronic diseases. But it can be hard to lose weight – especially given all the adaptations our body has to prevent it from happening.

Thankfully, small, sustainable changes that lead to gradual weight loss appear to be more effective in the long run, compared with more drastic lifestyle changes.

Alexandra Cremona, Lecturer, Human Nutrition and Dietetics, University of Limerick

This article is republished from The Conversation under a Creative Commons license. Read the original article.