0

For horses · Oct 20, 2023

Half your horses are overweight, and you probably can’t tell

Up to half of all horses are carrying too much weight, yet most owners don’t spot it, and the knock-on health problems are serious enough to take a proper look.

Chestnut horse standing in a show ring used to assess body condition score for equine obesity

By Beryl Shuttleworth, BSc Hons Biochem

Last reviewed: 2026-06-12

Chances are, your horse is carrying more weight than you think, studies show that between 20 and 51 percent of horses and ponies are overweight or obese, and most owners don’t realise it. A simple way to cheque: use the 9-point Henneke Body Condition Score system once a month. A score of 7 or above means there’s too much weight on board. And this matters beyond looks, excess weight raises the real risk of laminitis, insulin problems, equine metabolic syndrome, and hyperlipemia. It’s a health issue, full stop.

If a horse looks “normal,” its weight is fine

I hear this one all the time, and honestly, I get it. You see your horse every single day, and your eye adjusts to what’s familiar. But the research tells a different story: owners routinely underestimate whether their horses are carrying too much weight [2]. And when you consider that somewhere between 20 and 51 percent of horses and ponies are already overweight or obese [2], “looks normal to me” turns out to be a pretty unreliable yardstick.

Why does it matter? Because the knock-on effects of a horse carrying too much condition are serious and they build up over time. Extra weight puts horses at real risk of metabolic syndrome, insulin problems, laminitis, poor exercise tolerance, and joint issues, among other things [3]. Fat tissue isn’t just passive ballast either, it actively drives low-level inflammation and pushes insulin levels up in ways that are genuinely bad news for hoof health [9]. The gap between “pleasantly round” and a laminitis episode is shorter than most owners realise.

The good news is that you can get objective about this. The 9-point Henneke body condition scoring system gives you a reliable, hands-on way to assess your horse that your eye alone simply can’t match [1]. Run your hands along the ribs, feel the neck crest, cheque the fat pads at the withers and tailhead, that physical information is far more honest than a quick glance. Score monthly, keep a note of it, and trust the numbers. Your horse can’t tell you it’s uncomfortable carrying extra weight. The scoring system can.

How excess weight damages the horse from the inside out

Carrying too much weight doesn’t just put extra strain on a horse’s legs, the real damage starts inside the body, at the level of the tissues themselves. In horses with equine metabolic syndrome (EMS), fat tissue stops working as it should. It starts pumping out inflammatory signals and pushes insulin levels higher than they should ever be. That persistently raised insulin is what damages the delicate internal structures of the hoof, which is why obesity is such a reliable precursor to laminitis. It’s not simply a case of too much weight on the foot; it’s a whole-body hormonal and inflammatory problem [9].

Insulin dysregulation is really the heart of it. The more excess fat accumulates, the worse a horse’s insulin sensitivity tends to become [9]. The encouraging thing is that this can be turned around. A structured programme combining careful dietary restriction, around 85 percent of normal digestible energy intake, with moderate exercise five days a week has been shown to meaningfully reduce body condition score, shrink adipose deposits, and improve insulin sensitivity over ten weeks [8].

On the digestive side, horses evolved to spend most of their day grazing, and their guts are built around that. When they don’t get enough forage, at least 1.5 percent of body weight every day, with a minimum of eight hours’ foraging time, the whole system starts to struggle. Gut motility slows, pH balance shifts, and the risk of equine gastric ulcer syndrome (EGUS), colic, and stress-related behavioural issues goes up [4][5]. High-starch concentrate meals make things worse: more than 2 grams of starch per kilogram of body weight in a single meal creates an unfavourable gut environment and significantly raises the risk of ulcers and colic [6].

Two natural ingredients have some decent evidence behind them here. Arthrospira platensis (spirulina), when enriched with chromium, magnesium, and manganese, has been shown to lower baseline insulin and glucose levels, reduce body weight and cresty neck scores, bring triglycerides down, and reduce markers of liver fat and inflammation in horses with EMS, suggesting the mineral cofactors work alongside the algae to tackle the insulin problem directly [10].

Jerusalem artichoke meal is worth a mention too. It delivers fructooligosaccharides and inulin, natural prebiotic fibres, that have been shown to increase beneficial Lactobacillus bacteria and reduce Streptococcus in the equine hindgut. That’s not just adding bulk; it’s actively shifting the microbial balance in the right direction [11].

How to manage your horse’s weight: what the evidence actually supports

Start with an honest assessment

Before you change a single thing in your horse’s routine, grab a body condition score. The Henneke 9-point system is the gold standard, and it works best when you actually run your hands over your horse rather than eyeballing them from across the field. Feel the ribs, the neck crest, the withers, the tailhead, the rump. Research shows that owners consistently underestimate how heavy their horses are, so be honest with yourself. Score monthly, write it down, and you’ll have real evidence of whether things are improving. [1, 2]

Forage: the one thing you cannot cut

Whatever else changes, hay must not drop below 1.5 percent of your horse’s body weight per day (measured on a dry matter basis). This isn’t just about calories, it’s about keeping the gut working as it should. Horses evolved to be trickle feeders, spending at least 8 hours a day grazing, and when they don’t get enough forage, you’re looking at a real risk of gastric ulcers, colic, and stress behaviours. [4, 5] If your horse needs to slim down, work within this boundary: small-hole hay nets, a mature lower-calorie hay, and weighed portions rather than rough estimates. Do not simply slash the hay ration and hope for the best, the gut won’t thank you for it. [5]

Ditch the grain

Most healthy adult horses in light work simply don’t need grain-based concentrates. Feeding starch above 2 g per kilogram of body weight per meal, or letting concentrates creep above 40 percent of the total diet, significantly raises the risk of gastric ulcers and colic. If your horse is overweight or showing any signs of metabolic trouble, concentrates should be the very first thing off the menu. [6]

Move them, too, diet alone won’t cut it

Cutting calories helps, but it works far better when you pair it with regular, gentle exercise. A study in obese equids found that combining calorie restriction (set at 85 percent of their digestible energy needs) with moderate exercise five days a week produced real, measurable reductions in body condition score and fat deposits over just 10 weeks, and improved insulin sensitivity on top of that. Neither the diet nor the exercise delivered the same results on its own. [8]

If EMS or insulin dysregulation is in the mix

Carrying too much weight puts horses at serious risk of laminitis, the link runs through elevated insulin levels and changes in how fat tissue behaves in the body. [3, 9] It’s a vicious cycle worth breaking early. Research has looked at supplementing horses with equine metabolic syndrome using Arthrospira platensis (spirulina) enriched with chromium, magnesium, and manganese; the horses receiving it showed lower insulin and glucose levels, reduced body weight and cresty neck scores, and better triglyceride readings. [10] Separately, prebiotic compounds from Jerusalem artichoke meal, specifically fructooligosaccharides and inulin, have been shown to shift the hindgut bacteria in a helpful direction, increasing beneficial Lactobacillus and crowding out Streptococcus. [11] There’s also a broader body of comparative research looking at plant-derived compounds that may help tackle insulin resistance at a biological level, though equine-specific clinical trial data for most of these remains limited at this stage. [12]

What we’d recommend


Ultimate Mix

Smart micronutrient support with Spirulina and gut-friendly prebiotics, without the extra calories your horse doesn’t need.

See the product

Frequently asked questions

How common is obesity in horses, and am I likely underestimating my horse’s weight?

More common than most owners realise. Studies from multiple countries put the figure at somewhere between 20 and 51 percent of horses and ponies, so nearly half in some populations. The tricky part? Owners consistently underestimate their horse’s weight. That’s not a failing; it’s a well-documented pattern. Which is exactly why having a proper, objective way to cheque really does make a difference.

What health problems does being overweight cause in horses?

The list is a serious one: metabolic syndrome, insulin resistance, laminitis, hyperlipemia, poor exercise tolerance, difficulty regulating body temperature, and osteoarthritis. Overweight horses are also at higher risk of a gut condition called strangulating lipoma, and mares can have reproductive problems too. This isn’t about looks, carrying too much weight is a direct driver of some of the most painful conditions a horse can face.

How do I assess my horse’s body condition objectively?

Use the Henneke Body Condition Scoring system, a well-validated 9-point scale that both owners and vets can use reliably. It gives you a consistent, repeatable way to assess where your horse is carrying fat and track how that changes over time. Score monthly and write it down. Small changes are much easier to spot in a notebook than by eye.

How much hay does a horse need when I’m trying to reduce its weight?

Even on a weight-loss plan, forage should never drop below 1.5 percent of your horse’s body weight per day (measured as dry matter), and your horse needs at least 8 hours a day of foraging time. Horses evolved to trickle-feed almost constantly, cut below that and you risk ulcers, colic, and stress-related behaviours. Trim the calories carefully, but always protect gut health first.

Does exercise actually help an overweight horse lose weight and improve insulin sensitivity?

Yes, and the combination of diet and movement matters more than either on its own. Research on overweight horses found that pairing controlled calorie reduction (around 85 percent of normal energy requirements) with moderate exercise five days a week led to meaningful drops in body condition score and fat deposits over ten weeks, plus real improvements in insulin sensitivity. Diet alone is slower and less effective.

Are there natural supplements that can support insulin sensitivity in horses with equine metabolic syndrome?

There’s promising evidence. Spirulina (Arthrospira platensis) enriched with chromium, magnesium, and manganese has been shown to reduce insulin and glucose levels, lower triglycerides, shrink cresty neck scores, and calm markers of liver inflammation in horses with metabolic syndrome. Broader research across species also points to various plant-based compounds that target the root mechanisms of insulin resistance, though large equine clinical trials are still limited.

Sources

We use cookies to keep the shop working, and with your permission to understand how the site is used and to measure our advertising. You can change this at any time.